diff --git a/pkg/sqltypes/sql_types_scalar_test.go b/pkg/sqltypes/sql_types_scalar_test.go
new file mode 100644
index 0000000..292a9f7
--- /dev/null
+++ b/pkg/sqltypes/sql_types_scalar_test.go
@@ -0,0 +1,157 @@
+package sqltypes
+
+import (
+	"database/sql/driver"
+	"encoding/json"
+	"math"
+	"testing"
+	"time"
+)
+
+func TestSqlNull_ValueScalarCases(t *testing.T) {
+	tests := []struct {
+		name  string
+		input SqlNull[any]
+		want  driver.Value
+	}{
+		{name: "invalid", input: SqlNull[any]{}, want: nil},
+		{name: "integer", input: Null[any](int64(42), true), want: int64(42)},
+		{name: "string", input: Null[any]("hello", true), want: "hello"},
+		{name: "boolean", input: Null[any](true, true), want: true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := tt.input.Value()
+			if err != nil {
+				t.Fatalf("Value returned error: %v", err)
+			}
+			if got != tt.want {
+				t.Errorf("Value() = %v (%T), want %v (%T)", got, got, tt.want, tt.want)
+			}
+		})
+	}
+}
+
+func TestSqlNull_Int64Conversions(t *testing.T) {
+	tests := []struct {
+		name  string
+		input SqlNull[any]
+		want  int64
+	}{
+		{name: "invalid", input: SqlNull[any]{}, want: 0},
+		{name: "signed integer", input: Null[any](int32(-12), true), want: -12},
+		{name: "unsigned integer", input: Null[any](uint16(12), true), want: 12},
+		{name: "float truncates", input: Null[any](float64(12.9), true), want: 12},
+		{name: "numeric string", input: Null[any]("123", true), want: 123},
+		{name: "invalid string", input: Null[any]("not a number", true), want: 0},
+		{name: "true", input: Null[any](true, true), want: 1},
+		{name: "false", input: Null[any](false, true), want: 0},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.input.Int64(); got != tt.want {
+				t.Errorf("Int64() = %d, want %d", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestSqlNull_Float64Conversions(t *testing.T) {
+	tests := []struct {
+		name  string
+		input SqlNull[any]
+		want  float64
+	}{
+		{name: "invalid", input: SqlNull[any]{}, want: 0},
+		{name: "float", input: Null[any](float32(1.25), true), want: 1.25},
+		{name: "signed integer", input: Null[any](int64(-12), true), want: -12},
+		{name: "unsigned integer", input: Null[any](uint16(12), true), want: 12},
+		{name: "numeric string", input: Null[any]("12.5", true), want: 12.5},
+		{name: "invalid string", input: Null[any]("not a number", true), want: 0},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := tt.input.Float64(); got != tt.want {
+				t.Errorf("Float64() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestSqlDate_JSONNullAndInvalid(t *testing.T) {
+	tests := []struct {
+		name  string
+		json  string
+		valid bool
+	}{
+		{name: "null", json: "null", valid: false},
+		{name: "invalid date", json: `"not-a-date"`, valid: false},
+		{name: "valid date", json: `"2024-01-15"`, valid: true},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var got SqlDate
+			if err := json.Unmarshal([]byte(tt.json), &got); err != nil {
+				t.Fatalf("UnmarshalJSON returned error: %v", err)
+			}
+			if got.Valid != tt.valid {
+				t.Errorf("Valid = %v, want %v", got.Valid, tt.valid)
+			}
+		})
+	}
+
+	if data, err := json.Marshal(SqlDate{}); err != nil {
+		t.Fatalf("MarshalJSON returned error: %v", err)
+	} else if string(data) != "null" {
+		t.Errorf("MarshalJSON() = %s, want null", data)
+	}
+}
+
+func TestSqlTypeNowConstructors(t *testing.T) {
+	before := time.Now()
+	timestamp := SqlTimeStampNow()
+	date := SqlDateNow()
+	tm := SqlTimeNow()
+	after := time.Now()
+
+	for name, got := range map[string]time.Time{
+		"timestamp": timestamp.Time(),
+		"date":      date.Time(),
+		"time":      tm.Time(),
+	} {
+		if !got.After(before) && !got.Equal(before) || got.After(after) {
+			t.Errorf("%s constructor returned %v outside [%v, %v]", name, got, before, after)
+		}
+	}
+	if !timestamp.Valid || !date.Valid || !tm.Valid {
+		t.Fatal("Now constructors must return valid values")
+	}
+}
+
+func TestNewSqlAndToJSONDT(t *testing.T) {
+	if got := NewSql[int64]("42"); !got.Valid || got.Val != 42 {
+		t.Errorf("NewSql[int64](\"42\") = %#v, want valid 42", got)
+	}
+	if got := NewSql[int64](nil); got.Valid {
+		t.Errorf("NewSql[int64](nil) = %#v, want invalid", got)
+	}
+	if got := NewSqlFloat32(1.5); !got.Valid || got.Val != 1.5 {
+		t.Errorf("NewSqlFloat32(1.5) = %#v, want valid 1.5", got)
+	}
+
+	when := time.Date(2024, 1, 15, 10, 30, 45, 0, time.UTC)
+	if got := ToJSONDT(when); got != "2024-01-15T10:30:45Z" {
+		t.Errorf("ToJSONDT() = %q, want RFC3339 timestamp", got)
+	}
+}
+
+func TestSqlNull_Float64PreservesInfinity(t *testing.T) {
+	got := Null[float64](math.Inf(1), true).Float64()
+	if !math.IsInf(got, 1) {
+		t.Errorf("Float64() = %v, want +Inf", got)
+	}
+}