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.

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