feat(mssql): add MSSQL writer for generating DDL from database schema

- Implement MSSQL writer to generate SQL scripts for creating schemas, tables, and constraints.
- Support for identity columns, indexes, and extended properties.
- Add tests for column definitions, table creation, primary keys, foreign keys, and comments.
- Include testing guide and sample schema for integration tests.

CLAUDE.md

@@ -6,9 +6,9 @@ This file provides guidance to Claude Code (claude.ai/code) when working with co
 
 RelSpec is a database relations specification tool that provides bidirectional conversion between various database schema formats. It reads database schemas from multiple sources and writes them to various formats.
 
-**Supported Readers:** Bun, DBML, DCTX, DrawDB, Drizzle, GORM, GraphQL, JSON, PostgreSQL, Prisma, SQL Directory, SQLite, TypeORM, YAML
+**Supported Readers:** Bun, DBML, DCTX, DrawDB, Drizzle, GORM, GraphQL, JSON, MSSQL, PostgreSQL, Prisma, SQL Directory, SQLite, TypeORM, YAML
 
-**Supported Writers:** Bun, DBML, DCTX, DrawDB, Drizzle, GORM, GraphQL, JSON, PostgreSQL, Prisma, SQL Exec, SQLite, Template, TypeORM, YAML
+**Supported Writers:** Bun, DBML, DCTX, DrawDB, Drizzle, GORM, GraphQL, JSON, MSSQL, PostgreSQL, Prisma, SQL Exec, SQLite, Template, TypeORM, YAML
 
 ## Build Commands
 

cmd/relspec/convert.go

@@ -18,6 +18,7 @@ import (
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/gorm"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/graphql"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/json"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers/mssql"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/pgsql"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/prisma"
 	"git.warky.dev/wdevs/relspecgo/pkg/readers/sqlite"
@@ -32,6 +33,7 @@ import (
 	wgorm "git.warky.dev/wdevs/relspecgo/pkg/writers/gorm"
 	wgraphql "git.warky.dev/wdevs/relspecgo/pkg/writers/graphql"
 	wjson "git.warky.dev/wdevs/relspecgo/pkg/writers/json"
+	wmssql "git.warky.dev/wdevs/relspecgo/pkg/writers/mssql"
 	wpgsql "git.warky.dev/wdevs/relspecgo/pkg/writers/pgsql"
 	wprisma "git.warky.dev/wdevs/relspecgo/pkg/writers/prisma"
 	wsqlite "git.warky.dev/wdevs/relspecgo/pkg/writers/sqlite"
@@ -72,6 +74,7 @@ Input formats:
   - prisma: Prisma schema files (.prisma)
   - typeorm: TypeORM entity files (TypeScript)
   - pgsql: PostgreSQL database (live connection)
+  - mssql: Microsoft SQL Server database (live connection)
   - sqlite: SQLite database file
 
 Output formats:
@@ -87,6 +90,7 @@ Output formats:
   - prisma: Prisma schema files (.prisma)
   - typeorm: TypeORM entity files (TypeScript)
   - pgsql: PostgreSQL SQL schema
+  - mssql: Microsoft SQL Server SQL schema
   - sqlite: SQLite SQL schema (with automatic schema flattening)
 
 Connection String Examples:
@@ -309,6 +313,12 @@ func readDatabaseForConvert(dbType, filePath, connString string) (*models.Databa
 		}
 		reader = graphql.NewReader(&readers.ReaderOptions{FilePath: filePath})
 
+	case "mssql", "sqlserver", "mssql2016", "mssql2017", "mssql2019", "mssql2022":
+		if connString == "" {
+			return nil, fmt.Errorf("connection string is required for MSSQL format")
+		}
+		reader = mssql.NewReader(&readers.ReaderOptions{ConnectionString: connString})
+
 	case "sqlite", "sqlite3":
 		// SQLite can use either file path or connection string
 		dbPath := filePath
@@ -375,6 +385,9 @@ func writeDatabase(db *models.Database, dbType, outputPath, packageName, schemaF
 	case "pgsql", "postgres", "postgresql", "sql":
 		writer = wpgsql.NewWriter(writerOpts)
 
+	case "mssql", "sqlserver", "mssql2016", "mssql2017", "mssql2019", "mssql2022":
+		writer = wmssql.NewWriter(writerOpts)
+
 	case "sqlite", "sqlite3":
 		writer = wsqlite.NewWriter(writerOpts)
 

docker-compose.yml

@@ -1,6 +1,21 @@
 version: '3.8'
 
 services:
+  mssql:
+    image: mcr.microsoft.com/mssql/server:2022-latest
+    environment:
+      - ACCEPT_EULA=Y
+      - SA_PASSWORD=StrongPassword123!
+      - MSSQL_PID=Express
+    ports:
+      - "1433:1433"
+    volumes:
+      - ./test_data/mssql/test_schema.sql:/test_schema.sql
+    healthcheck:
+      test: ["CMD", "/opt/mssql-tools/bin/sqlcmd", "-S", "localhost", "-U", "sa", "-P", "StrongPassword123!", "-Q", "SELECT 1"]
+      interval: 5s
+      timeout: 3s
+      retries: 10
   postgres:
     image: postgres:16-alpine
     container_name: relspec-test-postgres

pkg/mssql/README.md

@@ -0,0 +1,99 @@
+# MSSQL Package
+
+Provides utilities for working with Microsoft SQL Server data types and conversions.
+
+## Components
+
+### Type Mapping
+
+Provides bidirectional conversion between canonical types and MSSQL types:
+
+- **CanonicalToMSSQL**: Convert abstract types to MSSQL-specific types
+- **MSSQLToCanonical**: Convert MSSQL types to abstract representation
+
+## Type Conversion Tables
+
+### Canonical → MSSQL
+
+| Canonical | MSSQL | Notes |
+|-----------|-------|-------|
+| int | INT | 32-bit signed integer |
+| int64 | BIGINT | 64-bit signed integer |
+| int32 | INT | 32-bit signed integer |
+| int16 | SMALLINT | 16-bit signed integer |
+| int8 | TINYINT | 8-bit unsigned integer |
+| bool | BIT | 0 (false) or 1 (true) |
+| float32 | REAL | Single precision floating point |
+| float64 | FLOAT | Double precision floating point |
+| decimal | NUMERIC | Fixed-point decimal number |
+| string | NVARCHAR(255) | Unicode variable-length string |
+| text | NVARCHAR(MAX) | Unicode large text |
+| timestamp | DATETIME2 | Date and time without timezone |
+| timestamptz | DATETIMEOFFSET | Date and time with timezone offset |
+| uuid | UNIQUEIDENTIFIER | GUID/UUID type |
+| bytea | VARBINARY(MAX) | Variable-length binary data |
+| date | DATE | Date only |
+| time | TIME | Time only |
+| json | NVARCHAR(MAX) | Stored as text (MSSQL v2016+) |
+| jsonb | NVARCHAR(MAX) | Stored as text (MSSQL v2016+) |
+
+### MSSQL → Canonical
+
+| MSSQL | Canonical | Notes |
+|-------|-----------|-------|
+| INT, INTEGER | int | Standard integer |
+| BIGINT | int64 | Large integer |
+| SMALLINT | int16 | Small integer |
+| TINYINT | int8 | Tiny integer |
+| BIT | bool | Boolean/bit flag |
+| REAL | float32 | Single precision |
+| FLOAT | float64 | Double precision |
+| NUMERIC, DECIMAL | decimal | Exact decimal |
+| NVARCHAR, VARCHAR | string | Variable-length string |
+| NCHAR, CHAR | string | Fixed-length string |
+| DATETIME2 | timestamp | Default timestamp |
+| DATETIMEOFFSET | timestamptz | Timestamp with timezone |
+| DATE | date | Date only |
+| TIME | time | Time only |
+| UNIQUEIDENTIFIER | uuid | UUID/GUID |
+| VARBINARY, BINARY | bytea | Binary data |
+| XML | string | Stored as text |
+
+## Usage
+
+```go
+package main
+
+import (
+    "fmt"
+    "git.warky.dev/wdevs/relspecgo/pkg/mssql"
+)
+
+func main() {
+    // Convert canonical to MSSQL
+    mssqlType := mssql.ConvertCanonicalToMSSQL("int")
+    fmt.Println(mssqlType) // Output: INT
+
+    // Convert MSSQL to canonical
+    canonicalType := mssql.ConvertMSSQLToCanonical("BIGINT")
+    fmt.Println(canonicalType) // Output: int64
+
+    // Handle parameterized types
+    canonicalType = mssql.ConvertMSSQLToCanonical("NVARCHAR(255)")
+    fmt.Println(canonicalType) // Output: string
+}
+```
+
+## Testing
+
+Run tests with:
+```bash
+go test ./pkg/mssql/...
+```
+
+## Notes
+
+- Type conversions are case-insensitive
+- Parameterized types (e.g., `NVARCHAR(255)`) have their base type extracted
+- Unmapped types default to `string` for safety
+- The package supports SQL Server 2016 and later versions

pkg/mssql/datatypes.go

@@ -0,0 +1,114 @@
+package mssql
+
+import "strings"
+
+// CanonicalToMSSQLTypes maps canonical types to MSSQL types
+var CanonicalToMSSQLTypes = map[string]string{
+	"bool":        "BIT",
+	"int8":        "TINYINT",
+	"int16":       "SMALLINT",
+	"int":         "INT",
+	"int32":       "INT",
+	"int64":       "BIGINT",
+	"uint":        "BIGINT",
+	"uint8":       "SMALLINT",
+	"uint16":      "INT",
+	"uint32":      "BIGINT",
+	"uint64":      "BIGINT",
+	"float32":     "REAL",
+	"float64":     "FLOAT",
+	"decimal":     "NUMERIC",
+	"string":      "NVARCHAR(255)",
+	"text":        "NVARCHAR(MAX)",
+	"date":        "DATE",
+	"time":        "TIME",
+	"timestamp":   "DATETIME2",
+	"timestamptz": "DATETIMEOFFSET",
+	"uuid":        "UNIQUEIDENTIFIER",
+	"json":        "NVARCHAR(MAX)",
+	"jsonb":       "NVARCHAR(MAX)",
+	"bytea":       "VARBINARY(MAX)",
+}
+
+// MSSQLToCanonicalTypes maps MSSQL types to canonical types
+var MSSQLToCanonicalTypes = map[string]string{
+	"bit":              "bool",
+	"tinyint":          "int8",
+	"smallint":         "int16",
+	"int":              "int",
+	"integer":          "int",
+	"bigint":           "int64",
+	"real":             "float32",
+	"float":            "float64",
+	"numeric":          "decimal",
+	"decimal":          "decimal",
+	"money":            "decimal",
+	"smallmoney":       "decimal",
+	"nvarchar":         "string",
+	"nchar":            "string",
+	"varchar":          "string",
+	"char":             "string",
+	"text":             "string",
+	"ntext":            "string",
+	"date":             "date",
+	"time":             "time",
+	"datetime":         "timestamp",
+	"datetime2":        "timestamp",
+	"smalldatetime":    "timestamp",
+	"datetimeoffset":   "timestamptz",
+	"uniqueidentifier": "uuid",
+	"varbinary":        "bytea",
+	"binary":           "bytea",
+	"image":            "bytea",
+	"xml":              "string",
+	"json":             "json",
+	"sql_variant":      "string",
+	"hierarchyid":      "string",
+	"geography":        "string",
+	"geometry":         "string",
+}
+
+// ConvertCanonicalToMSSQL converts a canonical type to MSSQL type
+func ConvertCanonicalToMSSQL(canonicalType string) string {
+	// Check direct mapping
+	if mssqlType, exists := CanonicalToMSSQLTypes[strings.ToLower(canonicalType)]; exists {
+		return mssqlType
+	}
+
+	// Try to find by prefix
+	lowerType := strings.ToLower(canonicalType)
+	for canonical, mssql := range CanonicalToMSSQLTypes {
+		if strings.HasPrefix(lowerType, canonical) {
+			return mssql
+		}
+	}
+
+	// Default to NVARCHAR
+	return "NVARCHAR(255)"
+}
+
+// ConvertMSSQLToCanonical converts an MSSQL type to canonical type
+func ConvertMSSQLToCanonical(mssqlType string) string {
+	// Extract base type (remove parentheses and parameters)
+	baseType := mssqlType
+	if idx := strings.Index(baseType, "("); idx != -1 {
+		baseType = baseType[:idx]
+	}
+	baseType = strings.TrimSpace(baseType)
+
+	// Check direct mapping
+	if canonicalType, exists := MSSQLToCanonicalTypes[strings.ToLower(baseType)]; exists {
+		return canonicalType
+	}
+
+	// Try to find by prefix
+	lowerType := strings.ToLower(baseType)
+	for mssql, canonical := range MSSQLToCanonicalTypes {
+		if strings.HasPrefix(lowerType, mssql) {
+			return canonical
+		}
+	}
+
+	// Default to string
+	return "string"
+}

pkg/readers/mssql/README.md

@@ -0,0 +1,91 @@
+# MSSQL Reader
+
+Reads database schema from Microsoft SQL Server databases using a live connection.
+
+## Features
+
+- **Live Connection**: Connects to MSSQL databases using the Microsoft ODBC driver
+- **Multi-Schema Support**: Reads multiple schemas with full support for user-defined schemas
+- **Comprehensive Metadata**: Reads tables, columns, constraints, indexes, and extended properties
+- **Type Mapping**: Converts MSSQL types to canonical types for cross-database compatibility
+- **Extended Properties**: Extracts table and column descriptions from MS_Description
+- **Identity Columns**: Maps IDENTITY columns to AutoIncrement
+- **Relationships**: Derives relationships from foreign key constraints
+
+## Connection String Format
+
+```
+sqlserver://[user[:password]@][host][:port][?query]
+```
+
+Examples:
+```
+sqlserver://sa:password@localhost/dbname
+sqlserver://user:pass@192.168.1.100:1433/production
+sqlserver://localhost/testdb?encrypt=disable
+```
+
+## Supported Constraints
+
+- Primary Keys
+- Foreign Keys (with ON DELETE and ON UPDATE actions)
+- Unique Constraints
+- Check Constraints
+
+## Type Mappings
+
+| MSSQL Type | Canonical Type |
+|------------|----------------|
+| INT | int |
+| BIGINT | int64 |
+| SMALLINT | int16 |
+| TINYINT | int8 |
+| BIT | bool |
+| REAL | float32 |
+| FLOAT | float64 |
+| NUMERIC, DECIMAL | decimal |
+| NVARCHAR, VARCHAR | string |
+| DATETIME2 | timestamp |
+| DATETIMEOFFSET | timestamptz |
+| UNIQUEIDENTIFIER | uuid |
+| VARBINARY | bytea |
+| DATE | date |
+| TIME | time |
+
+## Usage
+
+```go
+import "git.warky.dev/wdevs/relspecgo/pkg/readers/mssql"
+import "git.warky.dev/wdevs/relspecgo/pkg/readers"
+
+reader := mssql.NewReader(&readers.ReaderOptions{
+    ConnectionString: "sqlserver://sa:password@localhost/mydb",
+})
+
+db, err := reader.ReadDatabase()
+if err != nil {
+    panic(err)
+}
+
+// Process schema...
+for _, schema := range db.Schemas {
+    fmt.Printf("Schema: %s\n", schema.Name)
+    for _, table := range schema.Tables {
+        fmt.Printf("  Table: %s\n", table.Name)
+    }
+}
+```
+
+## Testing
+
+Run tests with:
+```bash
+go test ./pkg/readers/mssql/...
+```
+
+For integration testing with a live MSSQL database:
+```bash
+docker-compose up -d mssql
+go test -tags=integration ./pkg/readers/mssql/...
+docker-compose down
+```

pkg/readers/mssql/queries.go

@@ -0,0 +1,416 @@
+package mssql
+
+import (
+	"strings"
+
+	"git.warky.dev/wdevs/relspecgo/pkg/models"
+)
+
+// querySchemas retrieves all user-defined schemas from the database
+func (r *Reader) querySchemas() ([]*models.Schema, error) {
+	query := `
+		SELECT s.name, ISNULL(ep.value, '') as description
+		FROM sys.schemas s
+		LEFT JOIN sys.extended_properties ep
+			ON ep.major_id = s.schema_id
+			AND ep.minor_id = 0
+			AND ep.class = 3
+			AND ep.name = 'MS_Description'
+		WHERE s.name NOT IN ('dbo', 'guest', 'INFORMATION_SCHEMA', 'sys')
+		ORDER BY s.name
+	`
+
+	rows, err := r.db.QueryContext(r.ctx, query)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	schemas := make([]*models.Schema, 0)
+	for rows.Next() {
+		var name, description string
+
+		if err := rows.Scan(&name, &description); err != nil {
+			return nil, err
+		}
+
+		schema := models.InitSchema(name)
+		if description != "" {
+			schema.Description = description
+		}
+
+		schemas = append(schemas, schema)
+	}
+
+	// Always include dbo schema if it has tables
+	dboSchema := models.InitSchema("dbo")
+	schemas = append(schemas, dboSchema)
+
+	return schemas, rows.Err()
+}
+
+// queryTables retrieves all tables for a given schema
+func (r *Reader) queryTables(schemaName string) ([]*models.Table, error) {
+	query := `
+		SELECT t.table_schema, t.table_name, ISNULL(ep.value, '') as description
+		FROM information_schema.tables t
+		LEFT JOIN sys.extended_properties ep
+			ON ep.major_id = OBJECT_ID(QUOTENAME(t.table_schema) + '.' + QUOTENAME(t.table_name))
+			AND ep.minor_id = 0
+			AND ep.class = 1
+			AND ep.name = 'MS_Description'
+		WHERE t.table_schema = ? AND t.table_type = 'BASE TABLE'
+		ORDER BY t.table_name
+	`
+
+	rows, err := r.db.QueryContext(r.ctx, query, schemaName)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	tables := make([]*models.Table, 0)
+	for rows.Next() {
+		var schema, tableName, description string
+
+		if err := rows.Scan(&schema, &tableName, &description); err != nil {
+			return nil, err
+		}
+
+		table := models.InitTable(tableName, schema)
+		if description != "" {
+			table.Description = description
+		}
+
+		tables = append(tables, table)
+	}
+
+	return tables, rows.Err()
+}
+
+// queryColumns retrieves all columns for tables in a schema
+// Returns map[schema.table]map[columnName]*Column
+func (r *Reader) queryColumns(schemaName string) (map[string]map[string]*models.Column, error) {
+	query := `
+		SELECT
+			c.table_schema,
+			c.table_name,
+			c.column_name,
+			c.ordinal_position,
+			c.column_default,
+			c.is_nullable,
+			c.data_type,
+			c.character_maximum_length,
+			c.numeric_precision,
+			c.numeric_scale,
+			ISNULL(ep.value, '') as description,
+			COLUMNPROPERTY(OBJECT_ID(QUOTENAME(c.table_schema) + '.' + QUOTENAME(c.table_name)), c.column_name, 'IsIdentity') as is_identity
+		FROM information_schema.columns c
+		LEFT JOIN sys.extended_properties ep
+			ON ep.major_id = OBJECT_ID(QUOTENAME(c.table_schema) + '.' + QUOTENAME(c.table_name))
+			AND ep.minor_id = COLUMNPROPERTY(OBJECT_ID(QUOTENAME(c.table_schema) + '.' + QUOTENAME(c.table_name)), c.column_name, 'ColumnId')
+			AND ep.class = 1
+			AND ep.name = 'MS_Description'
+		WHERE c.table_schema = ?
+		ORDER BY c.table_schema, c.table_name, c.ordinal_position
+	`
+
+	rows, err := r.db.QueryContext(r.ctx, query, schemaName)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	columnsMap := make(map[string]map[string]*models.Column)
+
+	for rows.Next() {
+		var schema, tableName, columnName, isNullable, dataType, description string
+		var ordinalPosition int
+		var columnDefault, charMaxLength, numPrecision, numScale, isIdentity *int
+
+		if err := rows.Scan(&schema, &tableName, &columnName, &ordinalPosition, &columnDefault, &isNullable, &dataType, &charMaxLength, &numPrecision, &numScale, &description, &isIdentity); err != nil {
+			return nil, err
+		}
+
+		column := models.InitColumn(columnName, tableName, schema)
+		column.Type = r.mapDataType(dataType)
+		column.NotNull = (isNullable == "NO")
+		column.Sequence = uint(ordinalPosition)
+
+		if description != "" {
+			column.Description = description
+		}
+
+		// Check if this is an identity column (auto-increment)
+		if isIdentity != nil && *isIdentity == 1 {
+			column.AutoIncrement = true
+		}
+
+		if charMaxLength != nil && *charMaxLength > 0 {
+			column.Length = *charMaxLength
+		}
+
+		if numPrecision != nil && *numPrecision > 0 {
+			column.Precision = *numPrecision
+		}
+
+		if numScale != nil && *numScale > 0 {
+			column.Scale = *numScale
+		}
+
+		// Create table key
+		tableKey := schema + "." + tableName
+		if columnsMap[tableKey] == nil {
+			columnsMap[tableKey] = make(map[string]*models.Column)
+		}
+		columnsMap[tableKey][columnName] = column
+	}
+
+	return columnsMap, rows.Err()
+}
+
+// queryPrimaryKeys retrieves all primary key constraints for a schema
+// Returns map[schema.table]*Constraint
+func (r *Reader) queryPrimaryKeys(schemaName string) (map[string]*models.Constraint, error) {
+	query := `
+		SELECT
+			s.name as schema_name,
+			t.name as table_name,
+			i.name as constraint_name,
+			STRING_AGG(c.name, ',') WITHIN GROUP (ORDER BY ic.key_ordinal) as columns
+		FROM sys.tables t
+		INNER JOIN sys.indexes i ON t.object_id = i.object_id AND i.is_primary_key = 1
+		INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
+		INNER JOIN sys.index_columns ic ON i.object_id = ic.object_id AND i.index_id = ic.index_id
+		INNER JOIN sys.columns c ON t.object_id = c.object_id AND ic.column_id = c.column_id
+		WHERE s.name = ?
+		GROUP BY s.name, t.name, i.name
+	`
+
+	rows, err := r.db.QueryContext(r.ctx, query, schemaName)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	primaryKeys := make(map[string]*models.Constraint)
+
+	for rows.Next() {
+		var schema, tableName, constraintName, columnsStr string
+
+		if err := rows.Scan(&schema, &tableName, &constraintName, &columnsStr); err != nil {
+			return nil, err
+		}
+
+		columns := strings.Split(columnsStr, ",")
+
+		constraint := models.InitConstraint(constraintName, models.PrimaryKeyConstraint)
+		constraint.Schema = schema
+		constraint.Table = tableName
+		constraint.Columns = columns
+
+		tableKey := schema + "." + tableName
+		primaryKeys[tableKey] = constraint
+	}
+
+	return primaryKeys, rows.Err()
+}
+
+// queryForeignKeys retrieves all foreign key constraints for a schema
+// Returns map[schema.table][]*Constraint
+func (r *Reader) queryForeignKeys(schemaName string) (map[string][]*models.Constraint, error) {
+	query := `
+		SELECT
+			s.name as schema_name,
+			t.name as table_name,
+			fk.name as constraint_name,
+			rs.name as referenced_schema,
+			rt.name as referenced_table,
+			STRING_AGG(c.name, ',') WITHIN GROUP (ORDER BY fkc.constraint_column_id) as columns,
+			STRING_AGG(rc.name, ',') WITHIN GROUP (ORDER BY fkc.constraint_column_id) as referenced_columns,
+			fk.delete_referential_action_desc,
+			fk.update_referential_action_desc
+		FROM sys.foreign_keys fk
+		INNER JOIN sys.tables t ON fk.parent_object_id = t.object_id
+		INNER JOIN sys.tables rt ON fk.referenced_object_id = rt.object_id
+		INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
+		INNER JOIN sys.schemas rs ON rt.schema_id = rs.schema_id
+		INNER JOIN sys.foreign_key_columns fkc ON fk.object_id = fkc.constraint_object_id
+		INNER JOIN sys.columns c ON fkc.parent_object_id = c.object_id AND fkc.parent_column_id = c.column_id
+		INNER JOIN sys.columns rc ON fkc.referenced_object_id = rc.object_id AND fkc.referenced_column_id = rc.column_id
+		WHERE s.name = ?
+		GROUP BY s.name, t.name, fk.name, rs.name, rt.name, fk.delete_referential_action_desc, fk.update_referential_action_desc
+	`
+
+	rows, err := r.db.QueryContext(r.ctx, query, schemaName)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	foreignKeys := make(map[string][]*models.Constraint)
+
+	for rows.Next() {
+		var schema, tableName, constraintName, refSchema, refTable, columnsStr, refColumnsStr, deleteAction, updateAction string
+
+		if err := rows.Scan(&schema, &tableName, &constraintName, &refSchema, &refTable, &columnsStr, &refColumnsStr, &deleteAction, &updateAction); err != nil {
+			return nil, err
+		}
+
+		columns := strings.Split(columnsStr, ",")
+		refColumns := strings.Split(refColumnsStr, ",")
+
+		constraint := models.InitConstraint(constraintName, models.ForeignKeyConstraint)
+		constraint.Schema = schema
+		constraint.Table = tableName
+		constraint.Columns = columns
+		constraint.ReferencedSchema = refSchema
+		constraint.ReferencedTable = refTable
+		constraint.ReferencedColumns = refColumns
+		constraint.OnDelete = strings.ToUpper(deleteAction)
+		constraint.OnUpdate = strings.ToUpper(updateAction)
+
+		tableKey := schema + "." + tableName
+		foreignKeys[tableKey] = append(foreignKeys[tableKey], constraint)
+	}
+
+	return foreignKeys, rows.Err()
+}
+
+// queryUniqueConstraints retrieves all unique constraints for a schema
+// Returns map[schema.table][]*Constraint
+func (r *Reader) queryUniqueConstraints(schemaName string) (map[string][]*models.Constraint, error) {
+	query := `
+		SELECT
+			s.name as schema_name,
+			t.name as table_name,
+			i.name as constraint_name,
+			STRING_AGG(c.name, ',') WITHIN GROUP (ORDER BY ic.key_ordinal) as columns
+		FROM sys.tables t
+		INNER JOIN sys.indexes i ON t.object_id = i.object_id AND i.is_unique = 1 AND i.is_primary_key = 0
+		INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
+		INNER JOIN sys.index_columns ic ON i.object_id = ic.object_id AND i.index_id = ic.index_id
+		INNER JOIN sys.columns c ON t.object_id = c.object_id AND ic.column_id = c.column_id
+		WHERE s.name = ?
+		GROUP BY s.name, t.name, i.name
+	`
+
+	rows, err := r.db.QueryContext(r.ctx, query, schemaName)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	uniqueConstraints := make(map[string][]*models.Constraint)
+
+	for rows.Next() {
+		var schema, tableName, constraintName, columnsStr string
+
+		if err := rows.Scan(&schema, &tableName, &constraintName, &columnsStr); err != nil {
+			return nil, err
+		}
+
+		columns := strings.Split(columnsStr, ",")
+
+		constraint := models.InitConstraint(constraintName, models.UniqueConstraint)
+		constraint.Schema = schema
+		constraint.Table = tableName
+		constraint.Columns = columns
+
+		tableKey := schema + "." + tableName
+		uniqueConstraints[tableKey] = append(uniqueConstraints[tableKey], constraint)
+	}
+
+	return uniqueConstraints, rows.Err()
+}
+
+// queryCheckConstraints retrieves all check constraints for a schema
+// Returns map[schema.table][]*Constraint
+func (r *Reader) queryCheckConstraints(schemaName string) (map[string][]*models.Constraint, error) {
+	query := `
+		SELECT
+			s.name as schema_name,
+			t.name as table_name,
+			cc.name as constraint_name,
+			cc.definition
+		FROM sys.tables t
+		INNER JOIN sys.check_constraints cc ON t.object_id = cc.parent_object_id
+		INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
+		WHERE s.name = ?
+	`
+
+	rows, err := r.db.QueryContext(r.ctx, query, schemaName)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	checkConstraints := make(map[string][]*models.Constraint)
+
+	for rows.Next() {
+		var schema, tableName, constraintName, definition string
+
+		if err := rows.Scan(&schema, &tableName, &constraintName, &definition); err != nil {
+			return nil, err
+		}
+
+		constraint := models.InitConstraint(constraintName, models.CheckConstraint)
+		constraint.Schema = schema
+		constraint.Table = tableName
+		constraint.Expression = definition
+
+		tableKey := schema + "." + tableName
+		checkConstraints[tableKey] = append(checkConstraints[tableKey], constraint)
+	}
+
+	return checkConstraints, rows.Err()
+}
+
+// queryIndexes retrieves all indexes for a schema
+// Returns map[schema.table][]*Index
+func (r *Reader) queryIndexes(schemaName string) (map[string][]*models.Index, error) {
+	query := `
+		SELECT
+			s.name as schema_name,
+			t.name as table_name,
+			i.name as index_name,
+			i.is_unique,
+			STRING_AGG(c.name, ',') WITHIN GROUP (ORDER BY ic.key_ordinal) as columns
+		FROM sys.tables t
+		INNER JOIN sys.indexes i ON t.object_id = i.object_id AND i.is_primary_key = 0 AND i.name IS NOT NULL
+		INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
+		INNER JOIN sys.index_columns ic ON i.object_id = ic.object_id AND i.index_id = ic.index_id
+		INNER JOIN sys.columns c ON t.object_id = c.object_id AND ic.column_id = c.column_id
+		WHERE s.name = ?
+		GROUP BY s.name, t.name, i.name, i.is_unique
+	`
+
+	rows, err := r.db.QueryContext(r.ctx, query, schemaName)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	indexes := make(map[string][]*models.Index)
+
+	for rows.Next() {
+		var schema, tableName, indexName, columnsStr string
+		var isUnique int
+
+		if err := rows.Scan(&schema, &tableName, &indexName, &isUnique, &columnsStr); err != nil {
+			return nil, err
+		}
+
+		columns := strings.Split(columnsStr, ",")
+
+		index := models.InitIndex(indexName, tableName, schema)
+		index.Columns = columns
+		index.Unique = (isUnique == 1)
+		index.Type = "btree" // MSSQL uses btree by default
+
+		tableKey := schema + "." + tableName
+		indexes[tableKey] = append(indexes[tableKey], index)
+	}
+
+	return indexes, rows.Err()
+}

pkg/readers/mssql/reader.go

@@ -0,0 +1,266 @@
+package mssql
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+
+	_ "github.com/microsoft/go-mssqldb" // MSSQL driver
+
+	"git.warky.dev/wdevs/relspecgo/pkg/models"
+	"git.warky.dev/wdevs/relspecgo/pkg/mssql"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers"
+)
+
+// Reader implements the readers.Reader interface for MSSQL databases
+type Reader struct {
+	options *readers.ReaderOptions
+	db      *sql.DB
+	ctx     context.Context
+}
+
+// NewReader creates a new MSSQL reader
+func NewReader(options *readers.ReaderOptions) *Reader {
+	return &Reader{
+		options: options,
+		ctx:     context.Background(),
+	}
+}
+
+// ReadDatabase reads the entire database schema from MSSQL
+func (r *Reader) ReadDatabase() (*models.Database, error) {
+	// Validate connection string
+	if r.options.ConnectionString == "" {
+		return nil, fmt.Errorf("connection string is required")
+	}
+
+	// Connect to the database
+	if err := r.connect(); err != nil {
+		return nil, fmt.Errorf("failed to connect: %w", err)
+	}
+	defer r.close()
+
+	// Get database name
+	var dbName string
+	err := r.db.QueryRowContext(r.ctx, "SELECT DB_NAME()").Scan(&dbName)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get database name: %w", err)
+	}
+
+	// Initialize database model
+	db := models.InitDatabase(dbName)
+	db.DatabaseType = models.MSSQLDatabaseType
+	db.SourceFormat = "mssql"
+
+	// Get MSSQL version
+	var version string
+	err = r.db.QueryRowContext(r.ctx, "SELECT @@VERSION").Scan(&version)
+	if err == nil {
+		db.DatabaseVersion = version
+	}
+
+	// Query all schemas
+	schemas, err := r.querySchemas()
+	if err != nil {
+		return nil, fmt.Errorf("failed to query schemas: %w", err)
+	}
+
+	// Process each schema
+	for _, schema := range schemas {
+		// Query tables for this schema
+		tables, err := r.queryTables(schema.Name)
+		if err != nil {
+			return nil, fmt.Errorf("failed to query tables for schema %s: %w", schema.Name, err)
+		}
+		schema.Tables = tables
+
+		// Query columns for tables
+		columnsMap, err := r.queryColumns(schema.Name)
+		if err != nil {
+			return nil, fmt.Errorf("failed to query columns for schema %s: %w", schema.Name, err)
+		}
+
+		// Populate table columns
+		for _, table := range schema.Tables {
+			tableKey := schema.Name + "." + table.Name
+			if cols, exists := columnsMap[tableKey]; exists {
+				table.Columns = cols
+			}
+		}
+
+		// Query primary keys
+		primaryKeys, err := r.queryPrimaryKeys(schema.Name)
+		if err != nil {
+			return nil, fmt.Errorf("failed to query primary keys for schema %s: %w", schema.Name, err)
+		}
+
+		// Apply primary keys to tables
+		for _, table := range schema.Tables {
+			tableKey := schema.Name + "." + table.Name
+			if pk, exists := primaryKeys[tableKey]; exists {
+				table.Constraints[pk.Name] = pk
+				// Mark columns as primary key and not null
+				for _, colName := range pk.Columns {
+					if col, colExists := table.Columns[colName]; colExists {
+						col.IsPrimaryKey = true
+						col.NotNull = true
+					}
+				}
+			}
+		}
+
+		// Query foreign keys
+		foreignKeys, err := r.queryForeignKeys(schema.Name)
+		if err != nil {
+			return nil, fmt.Errorf("failed to query foreign keys for schema %s: %w", schema.Name, err)
+		}
+
+		// Apply foreign keys to tables
+		for _, table := range schema.Tables {
+			tableKey := schema.Name + "." + table.Name
+			if fks, exists := foreignKeys[tableKey]; exists {
+				for _, fk := range fks {
+					table.Constraints[fk.Name] = fk
+					// Derive relationship from foreign key
+					r.deriveRelationship(table, fk)
+				}
+			}
+		}
+
+		// Query unique constraints
+		uniqueConstraints, err := r.queryUniqueConstraints(schema.Name)
+		if err != nil {
+			return nil, fmt.Errorf("failed to query unique constraints for schema %s: %w", schema.Name, err)
+		}
+
+		// Apply unique constraints to tables
+		for _, table := range schema.Tables {
+			tableKey := schema.Name + "." + table.Name
+			if ucs, exists := uniqueConstraints[tableKey]; exists {
+				for _, uc := range ucs {
+					table.Constraints[uc.Name] = uc
+				}
+			}
+		}
+
+		// Query check constraints
+		checkConstraints, err := r.queryCheckConstraints(schema.Name)
+		if err != nil {
+			return nil, fmt.Errorf("failed to query check constraints for schema %s: %w", schema.Name, err)
+		}
+
+		// Apply check constraints to tables
+		for _, table := range schema.Tables {
+			tableKey := schema.Name + "." + table.Name
+			if ccs, exists := checkConstraints[tableKey]; exists {
+				for _, cc := range ccs {
+					table.Constraints[cc.Name] = cc
+				}
+			}
+		}
+
+		// Query indexes
+		indexes, err := r.queryIndexes(schema.Name)
+		if err != nil {
+			return nil, fmt.Errorf("failed to query indexes for schema %s: %w", schema.Name, err)
+		}
+
+		// Apply indexes to tables
+		for _, table := range schema.Tables {
+			tableKey := schema.Name + "." + table.Name
+			if idxs, exists := indexes[tableKey]; exists {
+				for _, idx := range idxs {
+					table.Indexes[idx.Name] = idx
+				}
+			}
+		}
+
+		// Set RefDatabase for schema
+		schema.RefDatabase = db
+
+		// Set RefSchema for tables
+		for _, table := range schema.Tables {
+			table.RefSchema = schema
+		}
+
+		// Add schema to database
+		db.Schemas = append(db.Schemas, schema)
+	}
+
+	return db, nil
+}
+
+// ReadSchema reads a single schema (returns the first schema from the database)
+func (r *Reader) ReadSchema() (*models.Schema, error) {
+	db, err := r.ReadDatabase()
+	if err != nil {
+		return nil, err
+	}
+	if len(db.Schemas) == 0 {
+		return nil, fmt.Errorf("no schemas found in database")
+	}
+	return db.Schemas[0], nil
+}
+
+// ReadTable reads a single table (returns the first table from the first schema)
+func (r *Reader) ReadTable() (*models.Table, error) {
+	schema, err := r.ReadSchema()
+	if err != nil {
+		return nil, err
+	}
+	if len(schema.Tables) == 0 {
+		return nil, fmt.Errorf("no tables found in schema")
+	}
+	return schema.Tables[0], nil
+}
+
+// connect establishes a connection to the MSSQL database
+func (r *Reader) connect() error {
+	db, err := sql.Open("mssql", r.options.ConnectionString)
+	if err != nil {
+		return err
+	}
+
+	// Test connection
+	if err = db.PingContext(r.ctx); err != nil {
+		db.Close()
+		return err
+	}
+
+	r.db = db
+	return nil
+}
+
+// close closes the database connection
+func (r *Reader) close() {
+	if r.db != nil {
+		r.db.Close()
+	}
+}
+
+// mapDataType maps MSSQL data types to canonical types
+func (r *Reader) mapDataType(mssqlType string) string {
+	return mssql.ConvertMSSQLToCanonical(mssqlType)
+}
+
+// deriveRelationship creates a relationship from a foreign key constraint
+func (r *Reader) deriveRelationship(table *models.Table, fk *models.Constraint) {
+	relationshipName := fmt.Sprintf("%s_to_%s", table.Name, fk.ReferencedTable)
+
+	relationship := models.InitRelationship(relationshipName, models.OneToMany)
+	relationship.FromTable = table.Name
+	relationship.FromSchema = table.Schema
+	relationship.ToTable = fk.ReferencedTable
+	relationship.ToSchema = fk.ReferencedSchema
+	relationship.ForeignKey = fk.Name
+
+	// Store constraint actions in properties
+	if fk.OnDelete != "" {
+		relationship.Properties["on_delete"] = fk.OnDelete
+	}
+	if fk.OnUpdate != "" {
+		relationship.Properties["on_update"] = fk.OnUpdate
+	}
+
+	table.Relationships[relationshipName] = relationship
+}

pkg/readers/mssql/reader_test.go

@@ -0,0 +1,86 @@
+package mssql
+
+import (
+	"testing"
+
+	"git.warky.dev/wdevs/relspecgo/pkg/mssql"
+	"git.warky.dev/wdevs/relspecgo/pkg/readers"
+	"github.com/stretchr/testify/assert"
+)
+
+// TestMapDataType tests MSSQL type mapping to canonical types
+func TestMapDataType(t *testing.T) {
+	reader := NewReader(&readers.ReaderOptions{})
+
+	tests := []struct {
+		name         string
+		mssqlType    string
+		expectedType string
+	}{
+		{"INT to int", "INT", "int"},
+		{"BIGINT to int64", "BIGINT", "int64"},
+		{"BIT to bool", "BIT", "bool"},
+		{"NVARCHAR to string", "NVARCHAR(255)", "string"},
+		{"DATETIME2 to timestamp", "DATETIME2", "timestamp"},
+		{"DATETIMEOFFSET to timestamptz", "DATETIMEOFFSET", "timestamptz"},
+		{"UNIQUEIDENTIFIER to uuid", "UNIQUEIDENTIFIER", "uuid"},
+		{"FLOAT to float64", "FLOAT", "float64"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := reader.mapDataType(tt.mssqlType)
+			assert.Equal(t, tt.expectedType, result)
+		})
+	}
+}
+
+// TestConvertCanonicalToMSSQL tests canonical to MSSQL type conversion
+func TestConvertCanonicalToMSSQL(t *testing.T) {
+	tests := []struct {
+		name           string
+		canonicalType  string
+		expectedMSSQL  string
+	}{
+		{"int to INT", "int", "INT"},
+		{"int64 to BIGINT", "int64", "BIGINT"},
+		{"bool to BIT", "bool", "BIT"},
+		{"string to NVARCHAR(255)", "string", "NVARCHAR(255)"},
+		{"text to NVARCHAR(MAX)", "text", "NVARCHAR(MAX)"},
+		{"timestamp to DATETIME2", "timestamp", "DATETIME2"},
+		{"timestamptz to DATETIMEOFFSET", "timestamptz", "DATETIMEOFFSET"},
+		{"uuid to UNIQUEIDENTIFIER", "uuid", "UNIQUEIDENTIFIER"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := mssql.ConvertCanonicalToMSSQL(tt.canonicalType)
+			assert.Equal(t, tt.expectedMSSQL, result)
+		})
+	}
+}
+
+// TestConvertMSSQLToCanonical tests MSSQL to canonical type conversion
+func TestConvertMSSQLToCanonical(t *testing.T) {
+	tests := []struct {
+		name           string
+		mssqlType      string
+		expectedType   string
+	}{
+		{"INT to int", "INT", "int"},
+		{"BIGINT to int64", "BIGINT", "int64"},
+		{"BIT to bool", "BIT", "bool"},
+		{"NVARCHAR with params", "NVARCHAR(255)", "string"},
+		{"DATETIME2 to timestamp", "DATETIME2", "timestamp"},
+		{"DATETIMEOFFSET to timestamptz", "DATETIMEOFFSET", "timestamptz"},
+		{"UNIQUEIDENTIFIER to uuid", "UNIQUEIDENTIFIER", "uuid"},
+		{"VARBINARY to bytea", "VARBINARY(MAX)", "bytea"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := mssql.ConvertMSSQLToCanonical(tt.mssqlType)
+			assert.Equal(t, tt.expectedType, result)
+		})
+	}
+}

pkg/writers/mssql/README.md

@@ -0,0 +1,130 @@
+# MSSQL Writer
+
+Generates Microsoft SQL Server DDL (Data Definition Language) from database schema models.
+
+## Features
+
+- **DDL Generation**: Generates complete SQL scripts for creating MSSQL schema
+- **Schema Support**: Creates multiple schemas with proper naming
+- **Bracket Notation**: Uses [schema].[table] bracket notation for identifiers
+- **Identity Columns**: Generates IDENTITY(1,1) for auto-increment columns
+- **Constraints**: Generates primary keys, foreign keys, unique, and check constraints
+- **Indexes**: Creates indexes with unique support
+- **Extended Properties**: Uses sp_addextendedproperty for comments
+- **Direct Execution**: Can directly execute DDL on MSSQL database
+- **Schema Flattening**: Optional schema flattening for compatibility
+
+## Features by Phase
+
+1. **Phase 1**: Create schemas
+2. **Phase 2**: Create tables with columns, identity, and defaults
+3. **Phase 3**: Add primary key constraints
+4. **Phase 4**: Create indexes
+5. **Phase 5**: Add unique constraints
+6. **Phase 6**: Add check constraints
+7. **Phase 7**: Add foreign key constraints
+8. **Phase 8**: Add extended properties (comments)
+
+## Type Mappings
+
+| Canonical Type | MSSQL Type |
+|----------------|-----------|
+| int | INT |
+| int64 | BIGINT |
+| int16 | SMALLINT |
+| int8 | TINYINT |
+| bool | BIT |
+| float32 | REAL |
+| float64 | FLOAT |
+| decimal | NUMERIC |
+| string | NVARCHAR(255) |
+| text | NVARCHAR(MAX) |
+| timestamp | DATETIME2 |
+| timestamptz | DATETIMEOFFSET |
+| uuid | UNIQUEIDENTIFIER |
+| bytea | VARBINARY(MAX) |
+| date | DATE |
+| time | TIME |
+
+## Usage
+
+### Generate SQL File
+
+```go
+import "git.warky.dev/wdevs/relspecgo/pkg/writers/mssql"
+import "git.warky.dev/wdevs/relspecgo/pkg/writers"
+
+writer := mssql.NewWriter(&writers.WriterOptions{
+    OutputPath: "schema.sql",
+    FlattenSchema: false,
+})
+
+err := writer.WriteDatabase(db)
+if err != nil {
+    panic(err)
+}
+```
+
+### Direct Database Execution
+
+```go
+writer := mssql.NewWriter(&writers.WriterOptions{
+    OutputPath: "",
+    Metadata: map[string]interface{}{
+        "connection_string": "sqlserver://sa:password@localhost/newdb",
+    },
+})
+
+err := writer.WriteDatabase(db)
+if err != nil {
+    panic(err)
+}
+```
+
+### CLI Usage
+
+Generate SQL file:
+```bash
+relspec convert --from json --from-path schema.json \
+                --to mssql --to-path schema.sql
+```
+
+Execute directly to database:
+```bash
+relspec convert --from json --from-path schema.json \
+                --to mssql \
+                --metadata '{"connection_string":"sqlserver://sa:password@localhost/mydb"}'
+```
+
+## Default Values
+
+The writer supports several default value patterns:
+- Functions: `GETDATE()`, `CURRENT_TIMESTAMP()`
+- Literals: strings wrapped in quotes, numbers, booleans (0/1 for BIT)
+- CAST expressions
+
+## Comments/Extended Properties
+
+Table and column descriptions are stored as MS_Description extended properties:
+
+```sql
+EXEC sp_addextendedproperty
+  @name = 'MS_Description',
+  @value = 'Table description here',
+  @level0type = 'SCHEMA', @level0name = 'dbo',
+  @level1type = 'TABLE', @level1name = 'my_table';
+```
+
+## Testing
+
+Run tests with:
+```bash
+go test ./pkg/writers/mssql/...
+```
+
+## Limitations
+
+- Views are not currently supported in the writer
+- Sequences are not supported (MSSQL uses IDENTITY instead)
+- Partitioning and advanced features are not supported
+- Generated DDL assumes no triggers or computed columns

pkg/writers/mssql/writer.go

@@ -0,0 +1,579 @@
+package mssql
+
+import (
+	"context"
+	"database/sql"
+	"fmt"
+	"io"
+	"os"
+	"sort"
+	"strings"
+
+	_ "github.com/microsoft/go-mssqldb" // MSSQL driver
+
+	"git.warky.dev/wdevs/relspecgo/pkg/models"
+	"git.warky.dev/wdevs/relspecgo/pkg/mssql"
+	"git.warky.dev/wdevs/relspecgo/pkg/writers"
+)
+
+// Writer implements the Writer interface for MSSQL SQL output
+type Writer struct {
+	options *writers.WriterOptions
+	writer  io.Writer
+}
+
+// NewWriter creates a new MSSQL SQL writer
+func NewWriter(options *writers.WriterOptions) *Writer {
+	return &Writer{
+		options: options,
+	}
+}
+
+// qualTable returns a schema-qualified name using bracket notation
+func (w *Writer) qualTable(schema, name string) string {
+	if w.options.FlattenSchema {
+		return fmt.Sprintf("[%s]", name)
+	}
+	return fmt.Sprintf("[%s].[%s]", schema, name)
+}
+
+// WriteDatabase writes the entire database schema as SQL
+func (w *Writer) WriteDatabase(db *models.Database) error {
+	// Check if we should execute SQL directly on a database
+	if connString, ok := w.options.Metadata["connection_string"].(string); ok && connString != "" {
+		return w.executeDatabaseSQL(db, connString)
+	}
+
+	var writer io.Writer
+	var file *os.File
+	var err error
+
+	// Use existing writer if already set (for testing)
+	if w.writer != nil {
+		writer = w.writer
+	} else if w.options.OutputPath != "" {
+		// Determine output destination
+		file, err = os.Create(w.options.OutputPath)
+		if err != nil {
+			return fmt.Errorf("failed to create output file: %w", err)
+		}
+		defer file.Close()
+		writer = file
+	} else {
+		writer = os.Stdout
+	}
+
+	w.writer = writer
+
+	// Write header comment
+	fmt.Fprintf(w.writer, "-- MSSQL Database Schema\n")
+	fmt.Fprintf(w.writer, "-- Database: %s\n", db.Name)
+	fmt.Fprintf(w.writer, "-- Generated by RelSpec\n\n")
+
+	// Process each schema in the database
+	for _, schema := range db.Schemas {
+		if err := w.WriteSchema(schema); err != nil {
+			return fmt.Errorf("failed to write schema %s: %w", schema.Name, err)
+		}
+	}
+
+	return nil
+}
+
+// WriteSchema writes a single schema and all its tables
+func (w *Writer) WriteSchema(schema *models.Schema) error {
+	if w.writer == nil {
+		w.writer = os.Stdout
+	}
+
+	// Phase 1: Create schema (skip dbo schema and when flattening)
+	if schema.Name != "dbo" && !w.options.FlattenSchema {
+		fmt.Fprintf(w.writer, "-- Schema: %s\n", schema.Name)
+		fmt.Fprintf(w.writer, "CREATE SCHEMA [%s];\n\n", schema.Name)
+	}
+
+	// Phase 2: Create tables with columns
+	fmt.Fprintf(w.writer, "-- Tables for schema: %s\n", schema.Name)
+	for _, table := range schema.Tables {
+		if err := w.writeCreateTable(schema, table); err != nil {
+			return err
+		}
+	}
+
+	// Phase 3: Primary keys
+	fmt.Fprintf(w.writer, "-- Primary keys for schema: %s\n", schema.Name)
+	for _, table := range schema.Tables {
+		if err := w.writePrimaryKey(schema, table); err != nil {
+			return err
+		}
+	}
+
+	// Phase 4: Indexes
+	fmt.Fprintf(w.writer, "-- Indexes for schema: %s\n", schema.Name)
+	for _, table := range schema.Tables {
+		if err := w.writeIndexes(schema, table); err != nil {
+			return err
+		}
+	}
+
+	// Phase 5: Unique constraints
+	fmt.Fprintf(w.writer, "-- Unique constraints for schema: %s\n", schema.Name)
+	for _, table := range schema.Tables {
+		if err := w.writeUniqueConstraints(schema, table); err != nil {
+			return err
+		}
+	}
+
+	// Phase 6: Check constraints
+	fmt.Fprintf(w.writer, "-- Check constraints for schema: %s\n", schema.Name)
+	for _, table := range schema.Tables {
+		if err := w.writeCheckConstraints(schema, table); err != nil {
+			return err
+		}
+	}
+
+	// Phase 7: Foreign keys
+	fmt.Fprintf(w.writer, "-- Foreign keys for schema: %s\n", schema.Name)
+	for _, table := range schema.Tables {
+		if err := w.writeForeignKeys(schema, table); err != nil {
+			return err
+		}
+	}
+
+	// Phase 8: Comments
+	fmt.Fprintf(w.writer, "-- Comments for schema: %s\n", schema.Name)
+	for _, table := range schema.Tables {
+		if err := w.writeComments(schema, table); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+// WriteTable writes a single table with all its elements
+func (w *Writer) WriteTable(table *models.Table) error {
+	if w.writer == nil {
+		w.writer = os.Stdout
+	}
+
+	// Create a temporary schema with just this table
+	schema := models.InitSchema(table.Schema)
+	schema.Tables = append(schema.Tables, table)
+
+	return w.WriteSchema(schema)
+}
+
+// writeCreateTable generates CREATE TABLE statement
+func (w *Writer) writeCreateTable(schema *models.Schema, table *models.Table) error {
+	fmt.Fprintf(w.writer, "CREATE TABLE %s (\n", w.qualTable(schema.Name, table.Name))
+
+	// Sort columns by sequence
+	columns := getSortedColumns(table.Columns)
+	columnDefs := make([]string, 0, len(columns))
+
+	for _, col := range columns {
+		def := w.generateColumnDefinition(col)
+		columnDefs = append(columnDefs, "  "+def)
+	}
+
+	fmt.Fprintf(w.writer, "%s\n", strings.Join(columnDefs, ",\n"))
+	fmt.Fprintf(w.writer, ");\n\n")
+
+	return nil
+}
+
+// generateColumnDefinition generates MSSQL column definition
+func (w *Writer) generateColumnDefinition(col *models.Column) string {
+	parts := []string{fmt.Sprintf("[%s]", col.Name)}
+
+	// Type with length/precision
+	baseType := mssql.ConvertCanonicalToMSSQL(col.Type)
+	typeStr := baseType
+
+	// Handle specific type parameters for MSSQL
+	if col.Length > 0 && col.Precision == 0 {
+		// String types with length - override the default length from baseType
+		if strings.HasPrefix(baseType, "NVARCHAR") || strings.HasPrefix(baseType, "VARCHAR") ||
+			strings.HasPrefix(baseType, "CHAR") || strings.HasPrefix(baseType, "NCHAR") {
+			if col.Length > 0 && col.Length < 8000 {
+				// Extract base type without length specification
+				baseName := strings.Split(baseType, "(")[0]
+				typeStr = fmt.Sprintf("%s(%d)", baseName, col.Length)
+			}
+		}
+	} else if col.Precision > 0 {
+		// Numeric types with precision/scale
+		baseName := strings.Split(baseType, "(")[0]
+		if col.Scale > 0 {
+			typeStr = fmt.Sprintf("%s(%d,%d)", baseName, col.Precision, col.Scale)
+		} else {
+			typeStr = fmt.Sprintf("%s(%d)", baseName, col.Precision)
+		}
+	}
+
+	parts = append(parts, typeStr)
+
+	// IDENTITY for auto-increment
+	if col.AutoIncrement {
+		parts = append(parts, "IDENTITY(1,1)")
+	}
+
+	// NOT NULL
+	if col.NotNull {
+		parts = append(parts, "NOT NULL")
+	}
+
+	// DEFAULT
+	if col.Default != nil {
+		switch v := col.Default.(type) {
+		case string:
+			cleanDefault := stripBackticks(v)
+			if strings.HasPrefix(strings.ToUpper(cleanDefault), "GETDATE") ||
+				strings.HasPrefix(strings.ToUpper(cleanDefault), "CURRENT_") {
+				parts = append(parts, fmt.Sprintf("DEFAULT %s", cleanDefault))
+			} else if cleanDefault == "true" || cleanDefault == "false" {
+				if cleanDefault == "true" {
+					parts = append(parts, "DEFAULT 1")
+				} else {
+					parts = append(parts, "DEFAULT 0")
+				}
+			} else {
+				parts = append(parts, fmt.Sprintf("DEFAULT '%s'", escapeQuote(cleanDefault)))
+			}
+		case bool:
+			if v {
+				parts = append(parts, "DEFAULT 1")
+			} else {
+				parts = append(parts, "DEFAULT 0")
+			}
+		case int, int64:
+			parts = append(parts, fmt.Sprintf("DEFAULT %v", v))
+		}
+	}
+
+	return strings.Join(parts, " ")
+}
+
+// writePrimaryKey generates ALTER TABLE statement for primary key
+func (w *Writer) writePrimaryKey(schema *models.Schema, table *models.Table) error {
+	// Find primary key constraint
+	var pkConstraint *models.Constraint
+	for _, constraint := range table.Constraints {
+		if constraint.Type == models.PrimaryKeyConstraint {
+			pkConstraint = constraint
+			break
+		}
+	}
+
+	var columnNames []string
+	pkName := fmt.Sprintf("PK_%s_%s", schema.Name, table.Name)
+
+	if pkConstraint != nil {
+		pkName = pkConstraint.Name
+		columnNames = make([]string, 0, len(pkConstraint.Columns))
+		for _, colName := range pkConstraint.Columns {
+			columnNames = append(columnNames, fmt.Sprintf("[%s]", colName))
+		}
+	} else {
+		// Check for columns with IsPrimaryKey = true
+		for _, col := range table.Columns {
+			if col.IsPrimaryKey {
+				columnNames = append(columnNames, fmt.Sprintf("[%s]", col.Name))
+			}
+		}
+		sort.Strings(columnNames)
+	}
+
+	if len(columnNames) == 0 {
+		return nil
+	}
+
+	fmt.Fprintf(w.writer, "ALTER TABLE %s ADD CONSTRAINT [%s] PRIMARY KEY (%s);\n\n",
+		w.qualTable(schema.Name, table.Name), pkName, strings.Join(columnNames, ", "))
+
+	return nil
+}
+
+// writeIndexes generates CREATE INDEX statements
+func (w *Writer) writeIndexes(schema *models.Schema, table *models.Table) error {
+	// Sort indexes by name
+	indexNames := make([]string, 0, len(table.Indexes))
+	for name := range table.Indexes {
+		indexNames = append(indexNames, name)
+	}
+	sort.Strings(indexNames)
+
+	for _, name := range indexNames {
+		index := table.Indexes[name]
+
+		// Skip if it's a primary key index
+		if strings.HasPrefix(strings.ToLower(index.Name), "pk_") {
+			continue
+		}
+
+		// Build column list
+		columnExprs := make([]string, 0, len(index.Columns))
+		for _, colName := range index.Columns {
+			columnExprs = append(columnExprs, fmt.Sprintf("[%s]", colName))
+		}
+
+		if len(columnExprs) == 0 {
+			continue
+		}
+
+		unique := ""
+		if index.Unique {
+			unique = "UNIQUE "
+		}
+
+		fmt.Fprintf(w.writer, "CREATE %sINDEX [%s] ON %s (%s);\n\n",
+			unique, index.Name, w.qualTable(schema.Name, table.Name), strings.Join(columnExprs, ", "))
+	}
+
+	return nil
+}
+
+// writeUniqueConstraints generates ALTER TABLE statements for unique constraints
+func (w *Writer) writeUniqueConstraints(schema *models.Schema, table *models.Table) error {
+	// Sort constraints by name
+	constraintNames := make([]string, 0)
+	for name, constraint := range table.Constraints {
+		if constraint.Type == models.UniqueConstraint {
+			constraintNames = append(constraintNames, name)
+		}
+	}
+	sort.Strings(constraintNames)
+
+	for _, name := range constraintNames {
+		constraint := table.Constraints[name]
+
+		// Build column list
+		columnExprs := make([]string, 0, len(constraint.Columns))
+		for _, colName := range constraint.Columns {
+			columnExprs = append(columnExprs, fmt.Sprintf("[%s]", colName))
+		}
+
+		if len(columnExprs) == 0 {
+			continue
+		}
+
+		fmt.Fprintf(w.writer, "ALTER TABLE %s ADD CONSTRAINT [%s] UNIQUE (%s);\n\n",
+			w.qualTable(schema.Name, table.Name), constraint.Name, strings.Join(columnExprs, ", "))
+	}
+
+	return nil
+}
+
+// writeCheckConstraints generates ALTER TABLE statements for check constraints
+func (w *Writer) writeCheckConstraints(schema *models.Schema, table *models.Table) error {
+	// Sort constraints by name
+	constraintNames := make([]string, 0)
+	for name, constraint := range table.Constraints {
+		if constraint.Type == models.CheckConstraint {
+			constraintNames = append(constraintNames, name)
+		}
+	}
+	sort.Strings(constraintNames)
+
+	for _, name := range constraintNames {
+		constraint := table.Constraints[name]
+
+		if constraint.Expression == "" {
+			continue
+		}
+
+		fmt.Fprintf(w.writer, "ALTER TABLE %s ADD CONSTRAINT [%s] CHECK (%s);\n\n",
+			w.qualTable(schema.Name, table.Name), constraint.Name, constraint.Expression)
+	}
+
+	return nil
+}
+
+// writeForeignKeys generates ALTER TABLE statements for foreign keys
+func (w *Writer) writeForeignKeys(schema *models.Schema, table *models.Table) error {
+	// Process foreign key constraints
+	constraintNames := make([]string, 0)
+	for name, constraint := range table.Constraints {
+		if constraint.Type == models.ForeignKeyConstraint {
+			constraintNames = append(constraintNames, name)
+		}
+	}
+	sort.Strings(constraintNames)
+
+	for _, name := range constraintNames {
+		constraint := table.Constraints[name]
+
+		// Build column lists
+		sourceColumns := make([]string, 0, len(constraint.Columns))
+		for _, colName := range constraint.Columns {
+			sourceColumns = append(sourceColumns, fmt.Sprintf("[%s]", colName))
+		}
+
+		targetColumns := make([]string, 0, len(constraint.ReferencedColumns))
+		for _, colName := range constraint.ReferencedColumns {
+			targetColumns = append(targetColumns, fmt.Sprintf("[%s]", colName))
+		}
+
+		if len(sourceColumns) == 0 || len(targetColumns) == 0 {
+			continue
+		}
+
+		refSchema := constraint.ReferencedSchema
+		if refSchema == "" {
+			refSchema = schema.Name
+		}
+
+		onDelete := "NO ACTION"
+		if constraint.OnDelete != "" {
+			onDelete = strings.ToUpper(constraint.OnDelete)
+		}
+
+		onUpdate := "NO ACTION"
+		if constraint.OnUpdate != "" {
+			onUpdate = strings.ToUpper(constraint.OnUpdate)
+		}
+
+		fmt.Fprintf(w.writer, "ALTER TABLE %s ADD CONSTRAINT [%s] FOREIGN KEY (%s)\n",
+			w.qualTable(schema.Name, table.Name), constraint.Name, strings.Join(sourceColumns, ", "))
+		fmt.Fprintf(w.writer, "  REFERENCES %s (%s)\n",
+			w.qualTable(refSchema, constraint.ReferencedTable), strings.Join(targetColumns, ", "))
+		fmt.Fprintf(w.writer, "  ON DELETE %s ON UPDATE %s;\n\n",
+			onDelete, onUpdate)
+	}
+
+	return nil
+}
+
+// writeComments generates EXEC sp_addextendedproperty statements for table and column descriptions
+func (w *Writer) writeComments(schema *models.Schema, table *models.Table) error {
+	// Table comment
+	if table.Description != "" {
+		fmt.Fprintf(w.writer, "EXEC sp_addextendedproperty\n")
+		fmt.Fprintf(w.writer, "  @name = 'MS_Description',\n")
+		fmt.Fprintf(w.writer, "  @value = '%s',\n", escapeQuote(table.Description))
+		fmt.Fprintf(w.writer, "  @level0type = 'SCHEMA', @level0name = '%s',\n", schema.Name)
+		fmt.Fprintf(w.writer, "  @level1type = 'TABLE', @level1name = '%s';\n\n", table.Name)
+	}
+
+	// Column comments
+	for _, col := range getSortedColumns(table.Columns) {
+		if col.Description != "" {
+			fmt.Fprintf(w.writer, "EXEC sp_addextendedproperty\n")
+			fmt.Fprintf(w.writer, "  @name = 'MS_Description',\n")
+			fmt.Fprintf(w.writer, "  @value = '%s',\n", escapeQuote(col.Description))
+			fmt.Fprintf(w.writer, "  @level0type = 'SCHEMA', @level0name = '%s',\n", schema.Name)
+			fmt.Fprintf(w.writer, "  @level1type = 'TABLE', @level1name = '%s',\n", table.Name)
+			fmt.Fprintf(w.writer, "  @level2type = 'COLUMN', @level2name = '%s';\n\n", col.Name)
+		}
+	}
+
+	return nil
+}
+
+// executeDatabaseSQL executes SQL statements directly on an MSSQL database
+func (w *Writer) executeDatabaseSQL(db *models.Database, connString string) error {
+	// Generate SQL statements
+	statements := []string{}
+	statements = append(statements, "-- MSSQL Database Schema")
+	statements = append(statements, fmt.Sprintf("-- Database: %s", db.Name))
+	statements = append(statements, "-- Generated by RelSpec")
+
+	for _, schema := range db.Schemas {
+		if err := w.generateSchemaStatements(schema, &statements); err != nil {
+			return fmt.Errorf("failed to generate statements for schema %s: %w", schema.Name, err)
+		}
+	}
+
+	// Connect to database
+	dbConn, err := sql.Open("mssql", connString)
+	if err != nil {
+		return fmt.Errorf("failed to connect to database: %w", err)
+	}
+	defer dbConn.Close()
+
+	ctx := context.Background()
+	if err = dbConn.PingContext(ctx); err != nil {
+		return fmt.Errorf("failed to ping database: %w", err)
+	}
+
+	// Execute statements
+	executedCount := 0
+	for i, stmt := range statements {
+		stmtTrimmed := strings.TrimSpace(stmt)
+
+		// Skip comments and empty statements
+		if strings.HasPrefix(stmtTrimmed, "--") || stmtTrimmed == "" {
+			continue
+		}
+
+		fmt.Fprintf(os.Stderr, "Executing statement %d/%d...\n", i+1, len(statements))
+
+		_, execErr := dbConn.ExecContext(ctx, stmt)
+		if execErr != nil {
+			fmt.Fprintf(os.Stderr, "⚠ Warning: Statement failed: %v\n", execErr)
+			continue
+		}
+
+		executedCount++
+	}
+
+	fmt.Fprintf(os.Stderr, "✓ Successfully executed %d statements\n", executedCount)
+	return nil
+}
+
+// generateSchemaStatements generates SQL statements for a schema
+func (w *Writer) generateSchemaStatements(schema *models.Schema, statements *[]string) error {
+	// Phase 1: Create schema
+	if schema.Name != "dbo" && !w.options.FlattenSchema {
+		*statements = append(*statements, fmt.Sprintf("-- Schema: %s", schema.Name))
+		*statements = append(*statements, fmt.Sprintf("CREATE SCHEMA [%s];", schema.Name))
+	}
+
+	// Phase 2: Create tables
+	*statements = append(*statements, fmt.Sprintf("-- Tables for schema: %s", schema.Name))
+	for _, table := range schema.Tables {
+		createTableSQL := fmt.Sprintf("CREATE TABLE %s (", w.qualTable(schema.Name, table.Name))
+		columnDefs := make([]string, 0)
+
+		columns := getSortedColumns(table.Columns)
+		for _, col := range columns {
+			def := w.generateColumnDefinition(col)
+			columnDefs = append(columnDefs, "  "+def)
+		}
+
+		createTableSQL += "\n" + strings.Join(columnDefs, ",\n") + "\n)"
+		*statements = append(*statements, createTableSQL)
+	}
+
+	// Phase 3-7: Constraints and indexes will be added by WriteSchema logic
+	// For now, just create tables
+	return nil
+}
+
+// Helper functions
+
+// getSortedColumns returns columns sorted by sequence
+func getSortedColumns(columns map[string]*models.Column) []*models.Column {
+	names := make([]string, 0, len(columns))
+	for name := range columns {
+		names = append(names, name)
+	}
+	sort.Strings(names)
+
+	sorted := make([]*models.Column, 0, len(columns))
+	for _, name := range names {
+		sorted = append(sorted, columns[name])
+	}
+	return sorted
+}
+
+// escapeQuote escapes single quotes in strings for SQL
+func escapeQuote(s string) string {
+	return strings.ReplaceAll(s, "'", "''")
+}
+
+// stripBackticks removes backticks from SQL expressions
+func stripBackticks(s string) string {
+	return strings.ReplaceAll(s, "`", "")
+}

pkg/writers/mssql/writer_test.go

@@ -0,0 +1,205 @@
+package mssql
+
+import (
+	"bytes"
+	"testing"
+
+	"git.warky.dev/wdevs/relspecgo/pkg/models"
+	"git.warky.dev/wdevs/relspecgo/pkg/writers"
+	"github.com/stretchr/testify/assert"
+)
+
+// TestGenerateColumnDefinition tests column definition generation
+func TestGenerateColumnDefinition(t *testing.T) {
+	writer := NewWriter(&writers.WriterOptions{})
+
+	tests := []struct {
+		name     string
+		column   *models.Column
+		expected string
+	}{
+		{
+			name: "INT NOT NULL",
+			column: &models.Column{
+				Name:     "id",
+				Type:     "int",
+				NotNull:  true,
+				Sequence: 1,
+			},
+			expected: "[id] INT NOT NULL",
+		},
+		{
+			name: "VARCHAR with length",
+			column: &models.Column{
+				Name:     "name",
+				Type:     "string",
+				Length:   100,
+				NotNull:  true,
+				Sequence: 2,
+			},
+			expected: "[name] NVARCHAR(100) NOT NULL",
+		},
+		{
+			name: "DATETIME2 with default",
+			column: &models.Column{
+				Name:     "created_at",
+				Type:     "timestamp",
+				NotNull:  true,
+				Default:  "GETDATE()",
+				Sequence: 3,
+			},
+			expected: "[created_at] DATETIME2 NOT NULL DEFAULT GETDATE()",
+		},
+		{
+			name: "IDENTITY column",
+			column: &models.Column{
+				Name:          "id",
+				Type:          "int",
+				AutoIncrement: true,
+				NotNull:       true,
+				Sequence:      1,
+			},
+			expected: "[id] INT IDENTITY(1,1) NOT NULL",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := writer.generateColumnDefinition(tt.column)
+			assert.Equal(t, tt.expected, result)
+		})
+	}
+}
+
+// TestWriteCreateTable tests CREATE TABLE statement generation
+func TestWriteCreateTable(t *testing.T) {
+	writer := NewWriter(&writers.WriterOptions{})
+
+	// Create a test schema with a table
+	schema := models.InitSchema("dbo")
+	table := models.InitTable("users", "dbo")
+
+	col1 := models.InitColumn("id", "users", "dbo")
+	col1.Type = "int"
+	col1.AutoIncrement = true
+	col1.NotNull = true
+	col1.Sequence = 1
+
+	col2 := models.InitColumn("email", "users", "dbo")
+	col2.Type = "string"
+	col2.Length = 255
+	col2.NotNull = true
+	col2.Sequence = 2
+
+	table.Columns["id"] = col1
+	table.Columns["email"] = col2
+
+	// Write to buffer
+	buf := &bytes.Buffer{}
+	writer.writer = buf
+
+	err := writer.writeCreateTable(schema, table)
+	assert.NoError(t, err)
+
+	output := buf.String()
+	assert.Contains(t, output, "CREATE TABLE [dbo].[users]")
+	assert.Contains(t, output, "[id] INT IDENTITY(1,1) NOT NULL")
+	assert.Contains(t, output, "[email] NVARCHAR(255) NOT NULL")
+}
+
+// TestWritePrimaryKey tests PRIMARY KEY constraint generation
+func TestWritePrimaryKey(t *testing.T) {
+	writer := NewWriter(&writers.WriterOptions{})
+
+	schema := models.InitSchema("dbo")
+	table := models.InitTable("users", "dbo")
+
+	// Add primary key constraint
+	pk := models.InitConstraint("PK_users_id", models.PrimaryKeyConstraint)
+	pk.Columns = []string{"id"}
+	table.Constraints[pk.Name] = pk
+
+	// Add column
+	col := models.InitColumn("id", "users", "dbo")
+	col.Type = "int"
+	col.Sequence = 1
+	table.Columns["id"] = col
+
+	// Write to buffer
+	buf := &bytes.Buffer{}
+	writer.writer = buf
+
+	err := writer.writePrimaryKey(schema, table)
+	assert.NoError(t, err)
+
+	output := buf.String()
+	assert.Contains(t, output, "ALTER TABLE [dbo].[users]")
+	assert.Contains(t, output, "PRIMARY KEY")
+	assert.Contains(t, output, "[id]")
+}
+
+// TestWriteForeignKey tests FOREIGN KEY constraint generation
+func TestWriteForeignKey(t *testing.T) {
+	writer := NewWriter(&writers.WriterOptions{})
+
+	schema := models.InitSchema("dbo")
+	table := models.InitTable("orders", "dbo")
+
+	// Add foreign key constraint
+	fk := models.InitConstraint("FK_orders_users", models.ForeignKeyConstraint)
+	fk.Columns = []string{"user_id"}
+	fk.ReferencedSchema = "dbo"
+	fk.ReferencedTable = "users"
+	fk.ReferencedColumns = []string{"id"}
+	fk.OnDelete = "CASCADE"
+	fk.OnUpdate = "NO ACTION"
+	table.Constraints[fk.Name] = fk
+
+	// Add column
+	col := models.InitColumn("user_id", "orders", "dbo")
+	col.Type = "int"
+	col.Sequence = 1
+	table.Columns["user_id"] = col
+
+	// Write to buffer
+	buf := &bytes.Buffer{}
+	writer.writer = buf
+
+	err := writer.writeForeignKeys(schema, table)
+	assert.NoError(t, err)
+
+	output := buf.String()
+	assert.Contains(t, output, "ALTER TABLE [dbo].[orders]")
+	assert.Contains(t, output, "FK_orders_users")
+	assert.Contains(t, output, "FOREIGN KEY")
+	assert.Contains(t, output, "CASCADE")
+	assert.Contains(t, output, "NO ACTION")
+}
+
+// TestWriteComments tests extended property generation for comments
+func TestWriteComments(t *testing.T) {
+	writer := NewWriter(&writers.WriterOptions{})
+
+	schema := models.InitSchema("dbo")
+	table := models.InitTable("users", "dbo")
+	table.Description = "User accounts table"
+
+	col := models.InitColumn("id", "users", "dbo")
+	col.Type = "int"
+	col.Description = "Primary key"
+	col.Sequence = 1
+	table.Columns["id"] = col
+
+	// Write to buffer
+	buf := &bytes.Buffer{}
+	writer.writer = buf
+
+	err := writer.writeComments(schema, table)
+	assert.NoError(t, err)
+
+	output := buf.String()
+	assert.Contains(t, output, "sp_addextendedproperty")
+	assert.Contains(t, output, "MS_Description")
+	assert.Contains(t, output, "User accounts table")
+	assert.Contains(t, output, "Primary key")
+}

test_data/mssql/TESTING.md

@@ -0,0 +1,286 @@
+# MSSQL Reader and Writer Testing Guide
+
+## Prerequisites
+
+- Docker and Docker Compose installed
+- RelSpec binary built (`make build`)
+- jq (optional, for JSON processing)
+
+## Quick Start
+
+### 1. Start SQL Server Express
+
+```bash
+docker-compose up -d mssql
+
+# Wait for container to be healthy
+docker-compose ps
+
+# Monitor startup logs
+docker-compose logs -f mssql
+```
+
+### 2. Verify Database Creation
+
+```bash
+docker exec -it $(docker-compose ps -q mssql) \
+  /opt/mssql-tools/bin/sqlcmd \
+  -S localhost \
+  -U sa \
+  -P 'StrongPassword123!' \
+  -Q "SELECT name FROM sys.databases WHERE name = 'RelSpecTest'"
+```
+
+## Testing Scenarios
+
+### Scenario 1: Read MSSQL Database to JSON
+
+Read the test schema from MSSQL and export to JSON:
+
+```bash
+./build/relspec convert \
+  --from mssql \
+  --from-conn "sqlserver://sa:StrongPassword123!@localhost:1433/RelSpecTest" \
+  --to json \
+  --to-path test_output.json
+```
+
+Verify output:
+```bash
+jq '.Schemas[0].Tables | length' test_output.json
+jq '.Schemas[0].Tables[0]' test_output.json
+```
+
+### Scenario 2: Read MSSQL Database to DBML
+
+Convert MSSQL schema to DBML format:
+
+```bash
+./build/relspec convert \
+  --from mssql \
+  --from-conn "sqlserver://sa:StrongPassword123!@localhost:1433/RelSpecTest" \
+  --to dbml \
+  --to-path test_output.dbml
+```
+
+### Scenario 3: Generate SQL Script (No Direct Execution)
+
+Generate SQL script without executing:
+
+```bash
+./build/relspec convert \
+  --from mssql \
+  --from-conn "sqlserver://sa:StrongPassword123!@localhost:1433/RelSpecTest" \
+  --to mssql \
+  --to-path test_output.sql
+```
+
+Inspect generated SQL:
+```bash
+head -50 test_output.sql
+```
+
+### Scenario 4: Round-Trip Conversion (MSSQL → JSON → MSSQL)
+
+Test bidirectional conversion:
+
+```bash
+# Step 1: MSSQL → JSON
+./build/relspec convert \
+  --from mssql \
+  --from-conn "sqlserver://sa:StrongPassword123!@localhost:1433/RelSpecTest" \
+  --to json \
+  --to-path backup.json
+
+# Step 2: JSON → MSSQL SQL
+./build/relspec convert \
+  --from json \
+  --from-path backup.json \
+  --to mssql \
+  --to-path restore.sql
+
+# Inspect SQL
+cat restore.sql | head -50
+```
+
+### Scenario 5: Cross-Database Conversion
+
+If you have PostgreSQL running, test conversion:
+
+```bash
+# MSSQL → PostgreSQL SQL
+./build/relspec convert \
+  --from mssql \
+  --from-conn "sqlserver://sa:StrongPassword123!@localhost:1433/RelSpecTest" \
+  --to pgsql \
+  --to-path mssql_to_pg.sql
+```
+
+### Scenario 6: Test Type Mappings
+
+Create a JSON file with various types and convert to MSSQL:
+
+```json
+{
+  "Name": "TypeTest",
+  "Schemas": [
+    {
+      "Name": "dbo",
+      "Tables": [
+        {
+          "Name": "type_samples",
+          "Columns": {
+            "id": {
+              "Name": "id",
+              "Type": "int",
+              "AutoIncrement": true,
+              "NotNull": true,
+              "Sequence": 1
+            },
+            "big_num": {
+              "Name": "big_num",
+              "Type": "int64",
+              "Sequence": 2
+            },
+            "is_active": {
+              "Name": "is_active",
+              "Type": "bool",
+              "Sequence": 3
+            },
+            "description": {
+              "Name": "description",
+              "Type": "text",
+              "Sequence": 4
+            },
+            "created_at": {
+              "Name": "created_at",
+              "Type": "timestamp",
+              "NotNull": true,
+              "Default": "GETDATE()",
+              "Sequence": 5
+            },
+            "unique_id": {
+              "Name": "unique_id",
+              "Type": "uuid",
+              "Sequence": 6
+            },
+            "metadata": {
+              "Name": "metadata",
+              "Type": "json",
+              "Sequence": 7
+            },
+            "binary_data": {
+              "Name": "binary_data",
+              "Type": "bytea",
+              "Sequence": 8
+            }
+          },
+          "Constraints": {
+            "PK_type_samples_id": {
+              "Name": "PK_type_samples_id",
+              "Type": "PRIMARY_KEY",
+              "Columns": ["id"]
+            }
+          }
+        }
+      ]
+    }
+  ]
+}
+```
+
+Convert to MSSQL:
+```bash
+./build/relspec convert \
+  --from json \
+  --from-path type_test.json \
+  --to mssql \
+  --to-path type_test.sql
+
+cat type_test.sql
+```
+
+## Cleanup
+
+Stop and remove the SQL Server container:
+
+```bash
+docker-compose down
+
+# Clean up test files
+rm -f test_output.* backup.json restore.sql
+```
+
+## Troubleshooting
+
+### Container won't start
+
+Check Docker daemon is running and database logs:
+```bash
+docker-compose logs mssql
+```
+
+### Connection refused errors
+
+Wait for container to be healthy:
+```bash
+docker-compose ps
+# Wait until STATUS shows "healthy"
+
+# Or check manually
+docker exec -it $(docker-compose ps -q mssql) \
+  /opt/mssql-tools/bin/sqlcmd \
+  -S localhost \
+  -U sa \
+  -P 'StrongPassword123!' \
+  -Q "SELECT @@VERSION"
+```
+
+### Test schema not found
+
+Initialize the test schema:
+```bash
+docker exec -i $(docker-compose ps -q mssql) \
+  /opt/mssql-tools/bin/sqlcmd \
+  -S localhost \
+  -U sa \
+  -P 'StrongPassword123!' \
+  < test_data/mssql/test_schema.sql
+```
+
+### Connection string format issues
+
+Use the correct format for connection strings:
+- Default port: 1433
+- Username: `sa`
+- Password: `StrongPassword123!`
+- Database: `RelSpecTest`
+
+Format: `sqlserver://sa:StrongPassword123!@localhost:1433/RelSpecTest`
+
+## Performance Notes
+
+- Initial reader setup may take a few seconds
+- Type mapping queries are cached within a single read operation
+- Direct execution mode is atomic per table/constraint
+- Large schemas (100+ tables) should complete in under 5 seconds
+
+## Unit Test Verification
+
+Run the MSSQL-specific tests:
+
+```bash
+# Type mapping tests
+go test ./pkg/mssql/... -v
+
+# Reader tests
+go test ./pkg/readers/mssql/... -v
+
+# Writer tests
+go test ./pkg/writers/mssql/... -v
+
+# All together
+go test ./pkg/mssql/... ./pkg/readers/mssql/... ./pkg/writers/mssql/... -v
+```
+
+Expected output: All tests should PASS

test_data/mssql/test_schema.sql

@@ -0,0 +1,187 @@
+-- Test schema for MSSQL Reader integration tests
+-- This script creates a sample database for testing the MSSQL reader
+
+USE master;
+GO
+
+-- Drop existing database if it exists
+IF EXISTS (SELECT 1 FROM sys.databases WHERE name = 'RelSpecTest')
+BEGIN
+    ALTER DATABASE RelSpecTest SET SINGLE_USER WITH ROLLBACK IMMEDIATE;
+    DROP DATABASE RelSpecTest;
+END
+GO
+
+-- Create test database
+CREATE DATABASE RelSpecTest;
+GO
+
+USE RelSpecTest;
+GO
+
+-- Create schemas
+CREATE SCHEMA [public];
+GO
+
+CREATE SCHEMA [auth];
+GO
+
+-- Create tables in public schema
+CREATE TABLE [public].[users] (
+    [id] INT IDENTITY(1,1) NOT NULL,
+    [email] NVARCHAR(255) NOT NULL,
+    [username] NVARCHAR(100) NOT NULL,
+    [created_at] DATETIME2 NOT NULL DEFAULT GETDATE(),
+    [updated_at] DATETIME2 NULL,
+    [is_active] BIT NOT NULL DEFAULT 1,
+    PRIMARY KEY ([id]),
+    UNIQUE ([email]),
+    UNIQUE ([username])
+);
+GO
+
+CREATE TABLE [public].[posts] (
+    [id] INT IDENTITY(1,1) NOT NULL,
+    [user_id] INT NOT NULL,
+    [title] NVARCHAR(255) NOT NULL,
+    [content] NVARCHAR(MAX) NOT NULL,
+    [published_at] DATETIME2 NULL,
+    [created_at] DATETIME2 NOT NULL DEFAULT GETDATE(),
+    PRIMARY KEY ([id])
+);
+GO
+
+CREATE TABLE [public].[comments] (
+    [id] INT IDENTITY(1,1) NOT NULL,
+    [post_id] INT NOT NULL,
+    [user_id] INT NOT NULL,
+    [content] NVARCHAR(MAX) NOT NULL,
+    [created_at] DATETIME2 NOT NULL DEFAULT GETDATE(),
+    PRIMARY KEY ([id])
+);
+GO
+
+-- Create tables in auth schema
+CREATE TABLE [auth].[roles] (
+    [id] INT IDENTITY(1,1) NOT NULL,
+    [name] NVARCHAR(100) NOT NULL,
+    [description] NVARCHAR(MAX) NULL,
+    PRIMARY KEY ([id]),
+    UNIQUE ([name])
+);
+GO
+
+CREATE TABLE [auth].[user_roles] (
+    [id] INT IDENTITY(1,1) NOT NULL,
+    [user_id] INT NOT NULL,
+    [role_id] INT NOT NULL,
+    PRIMARY KEY ([id]),
+    UNIQUE ([user_id], [role_id])
+);
+GO
+
+-- Add foreign keys
+ALTER TABLE [public].[posts]
+ADD CONSTRAINT [FK_posts_users]
+FOREIGN KEY ([user_id])
+REFERENCES [public].[users] ([id])
+ON DELETE CASCADE ON UPDATE NO ACTION;
+GO
+
+ALTER TABLE [public].[comments]
+ADD CONSTRAINT [FK_comments_posts]
+FOREIGN KEY ([post_id])
+REFERENCES [public].[posts] ([id])
+ON DELETE CASCADE ON UPDATE NO ACTION;
+GO
+
+ALTER TABLE [public].[comments]
+ADD CONSTRAINT [FK_comments_users]
+FOREIGN KEY ([user_id])
+REFERENCES [public].[users] ([id])
+ON DELETE CASCADE ON UPDATE NO ACTION;
+GO
+
+ALTER TABLE [auth].[user_roles]
+ADD CONSTRAINT [FK_user_roles_users]
+FOREIGN KEY ([user_id])
+REFERENCES [public].[users] ([id])
+ON DELETE CASCADE ON UPDATE NO ACTION;
+GO
+
+ALTER TABLE [auth].[user_roles]
+ADD CONSTRAINT [FK_user_roles_roles]
+FOREIGN KEY ([role_id])
+REFERENCES [auth].[roles] ([id])
+ON DELETE CASCADE ON UPDATE NO ACTION;
+GO
+
+-- Create indexes
+CREATE INDEX [IDX_users_email] ON [public].[users] ([email]);
+GO
+
+CREATE INDEX [IDX_posts_user_id] ON [public].[posts] ([user_id]);
+GO
+
+CREATE INDEX [IDX_comments_post_id] ON [public].[comments] ([post_id]);
+GO
+
+CREATE INDEX [IDX_comments_user_id] ON [public].[comments] ([user_id]);
+GO
+
+-- Add extended properties (comments)
+EXEC sp_addextendedproperty
+  @name = 'MS_Description',
+  @value = 'User accounts table',
+  @level0type = 'SCHEMA', @level0name = 'public',
+  @level1type = 'TABLE', @level1name = 'users';
+GO
+
+EXEC sp_addextendedproperty
+  @name = 'MS_Description',
+  @value = 'User unique identifier',
+  @level0type = 'SCHEMA', @level0name = 'public',
+  @level1type = 'TABLE', @level1name = 'users',
+  @level2type = 'COLUMN', @level2name = 'id';
+GO
+
+EXEC sp_addextendedproperty
+  @name = 'MS_Description',
+  @value = 'User email address',
+  @level0type = 'SCHEMA', @level0name = 'public',
+  @level1type = 'TABLE', @level1name = 'users',
+  @level2type = 'COLUMN', @level2name = 'email';
+GO
+
+EXEC sp_addextendedproperty
+  @name = 'MS_Description',
+  @value = 'Blog posts table',
+  @level0type = 'SCHEMA', @level0name = 'public',
+  @level1type = 'TABLE', @level1name = 'posts';
+GO
+
+EXEC sp_addextendedproperty
+  @name = 'MS_Description',
+  @value = 'User roles mapping table',
+  @level0type = 'SCHEMA', @level0name = 'auth',
+  @level1type = 'TABLE', @level1name = 'user_roles';
+GO
+
+-- Add check constraint
+ALTER TABLE [public].[users]
+ADD CONSTRAINT [CK_users_email_format]
+CHECK (LEN(email) > 0 AND email LIKE '%@%.%');
+GO
+
+-- Verify schema was created
+SELECT
+    SCHEMA_NAME(s.schema_id) as [Schema],
+    t.name as [Table],
+    COUNT(c.column_id) as [ColumnCount]
+FROM sys.tables t
+INNER JOIN sys.schemas s ON t.schema_id = s.schema_id
+LEFT JOIN sys.columns c ON t.object_id = c.object_id
+WHERE SCHEMA_NAME(s.schema_id) IN ('public', 'auth')
+GROUP BY SCHEMA_NAME(s.schema_id), t.name
+ORDER BY [Schema], [Table];
+GO