feat(db): implement SqlDialect with MySQL, SQL Server, PostgreSQL dialects

Add three SqlDialect implementations with a factory function:
- MySqlDialect: positional ?, ON DUPLICATE KEY UPDATE, LIMIT/OFFSET
- SqlServerDialect: @pN params, MERGE USING, OFFSET/FETCH
- PostgreSqlDialect: $N (1-based), ON CONFLICT DO UPDATE, LIMIT/OFFSET

TDD approach: 43 tests written first, all passing.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/main/services/database/dialects/index.ts

@@ -0,0 +1,27 @@
+/**
+ * SQL Dialect Factory
+ *
+ * Creates the appropriate SqlDialect implementation based on database type.
+ */
+
+import type { DatabaseType } from '@types/database.types'
+import type { SqlDialect } from '@types/sql-dialect.types'
+
+import { MySqlDialect } from './mysql-dialect'
+import { PostgreSqlDialect } from './postgresql-dialect'
+import { SqlServerDialect } from './sqlserver-dialect'
+
+export { MySqlDialect } from './mysql-dialect'
+export { PostgreSqlDialect } from './postgresql-dialect'
+export { SqlServerDialect } from './sqlserver-dialect'
+
+export function createDialect(type: DatabaseType): SqlDialect {
+  switch (type) {
+    case 'sqlserver':
+      return new SqlServerDialect()
+    case 'postgresql':
+      return new PostgreSqlDialect()
+    default:
+      return new MySqlDialect()
+  }
+}

src/main/services/database/dialects/mysql-dialect.ts

@@ -0,0 +1,73 @@
+/**
+ * MySQL SQL Dialect Implementation
+ *
+ * Encapsulates MySQL-specific SQL syntax for:
+ * - Table name quoting (underscore-separated)
+ * - Positional parameter placeholders (?)
+ * - INSERT ... ON DUPLICATE KEY UPDATE upsert
+ * - LIMIT/OFFSET pagination
+ */
+
+import type { SqlDialect } from '@types/sql-dialect.types'
+
+export class MySqlDialect implements SqlDialect {
+  readonly dbType = 'mysql' as const
+
+  quoteTableName(schema: string, table: string): string {
+    return `${schema}_${table}`
+  }
+
+  param(_index: number): string {
+    return '?'
+  }
+
+  params(count: number): string {
+    return Array.from({ length: count }, () => '?').join(',')
+  }
+
+  currentTimestamp(): string {
+    return 'NOW()'
+  }
+
+  upsert(params: {
+    table: string
+    keyColumns: string[]
+    allColumns: string[]
+    startParamIndex: number
+  }): { sql: string; nextParamIndex: number } {
+    const { table, keyColumns, allColumns, startParamIndex } = params
+
+    const columns = allColumns.join(', ')
+    const placeholders = allColumns.map(() => '?').join(', ')
+
+    const nonKeyColumns = allColumns.filter((col) => !keyColumns.includes(col))
+    const updateClause = nonKeyColumns
+      .map((col) => `${col} = VALUES(${col})`)
+      .join(', ')
+
+    const sql = `INSERT INTO ${table} (${columns}) VALUES (${placeholders}) ON DUPLICATE KEY UPDATE ${updateClause}`
+
+    return {
+      sql,
+      nextParamIndex: startParamIndex + allColumns.length
+    }
+  }
+
+  paginate(params: {
+    sql: string
+    limit: number
+    offset?: number
+    paramIndex: number
+  }): { sql: string; nextParamIndex: number } {
+    const { sql, limit, offset, paramIndex } = params
+
+    return {
+      sql: `${sql} LIMIT ${limit} OFFSET ${offset ?? 0}`,
+      nextParamIndex: paramIndex
+    }
+  }
+
+  maxBatchRows(_columnsPerRow: number): number {
+    return 1000
+  }
+}

src/main/services/database/dialects/postgresql-dialect.ts

@@ -0,0 +1,81 @@
+/**
+ * PostgreSQL Dialect Implementation
+ *
+ * Encapsulates PostgreSQL-specific SQL syntax for:
+ * - Table name quoting (double-quoted "schema"."table")
+ * - Positional parameter placeholders ($1, $2, ...) — 1-based
+ * - INSERT ... ON CONFLICT ... DO UPDATE SET upsert
+ * - LIMIT/OFFSET pagination
+ */
+
+import type { SqlDialect } from '@types/sql-dialect.types'
+
+export class PostgreSqlDialect implements SqlDialect {
+  readonly dbType = 'postgresql' as const
+
+  quoteTableName(schema: string, table: string): string {
+    return `"${schema}"."${table}"`
+  }
+
+  param(index: number): string {
+    return `$${index + 1}`
+  }
+
+  params(count: number): string {
+    return Array.from({ length: count }, (_, i) => `$${i + 1}`).join(',')
+  }
+
+  currentTimestamp(): string {
+    return 'CURRENT_TIMESTAMP'
+  }
+
+  upsert(params: {
+    table: string
+    keyColumns: string[]
+    allColumns: string[]
+    startParamIndex: number
+  }): { sql: string; nextParamIndex: number } {
+    const { table, keyColumns, allColumns, startParamIndex } = params
+
+    const columns = allColumns.join(', ')
+    const placeholders = allColumns
+      .map((_, i) => `$${startParamIndex + i + 1}`)
+      .join(', ')
+
+    const conflictKeys = keyColumns.map((col) => `"${col}"`).join(', ')
+
+    const nonKeyColumns = allColumns.filter((col) => !keyColumns.includes(col))
+    const updateSet = nonKeyColumns
+      .map((col) => `"${col}" = EXCLUDED."${col}"`)
+      .join(', ')
+
+    const sql = [
+      `INSERT INTO ${table} (${columns}) VALUES (${placeholders})`,
+      `ON CONFLICT (${conflictKeys})`,
+      `DO UPDATE SET ${updateSet}`
+    ].join(' ')
+
+    return {
+      sql,
+      nextParamIndex: startParamIndex + allColumns.length
+    }
+  }
+
+  paginate(params: {
+    sql: string
+    limit: number
+    offset?: number
+    paramIndex: number
+  }): { sql: string; nextParamIndex: number } {
+    const { sql, limit, offset, paramIndex } = params
+
+    return {
+      sql: `${sql} LIMIT ${limit} OFFSET ${offset ?? 0}`,
+      nextParamIndex: paramIndex
+    }
+  }
+
+  maxBatchRows(_columnsPerRow: number): number {
+    return 1000
+  }
+}

src/main/services/database/dialects/sqlserver-dialect.ts

@@ -0,0 +1,95 @@
+/**
+ * SQL Server Dialect Implementation
+ *
+ * Encapsulates SQL Server-specific SQL syntax for:
+ * - Table name quoting (bracket notation [schema].[table])
+ * - Named parameter placeholders (@p0, @p1, ...)
+ * - MERGE ... USING upsert
+ * - OFFSET/FETCH pagination
+ */
+
+import type { SqlDialect } from '@types/sql-dialect.types'
+
+export class SqlServerDialect implements SqlDialect {
+  readonly dbType = 'sqlserver' as const
+
+  quoteTableName(schema: string, table: string): string {
+    return `[${schema}].[${table}]`
+  }
+
+  param(index: number): string {
+    return `@p${index}`
+  }
+
+  params(count: number): string {
+    return Array.from({ length: count }, (_, i) => `@p${i}`).join(',')
+  }
+
+  currentTimestamp(): string {
+    return 'GETDATE()'
+  }
+
+  upsert(params: {
+    table: string
+    keyColumns: string[]
+    allColumns: string[]
+    startParamIndex: number
+  }): { sql: string; nextParamIndex: number } {
+    const { table, keyColumns, allColumns, startParamIndex } = params
+
+    const valueParams = allColumns
+      .map((_, i) => `@p${startParamIndex + i}`)
+      .join(', ')
+    const sourceColumns = allColumns.join(', ')
+
+    const joinCondition = keyColumns
+      .map((col) => `target.${col} = source.${col}`)
+      .join(' AND ')
+
+    const nonKeyColumns = allColumns.filter((col) => !keyColumns.includes(col))
+    const updateSet = nonKeyColumns
+      .map((col) => `target.${col} = source.${col}`)
+      .join(', ')
+
+    const insertColumns = allColumns.join(', ')
+    const insertValues = allColumns.map((col) => `source.${col}`).join(', ')
+
+    const sql = [
+      `MERGE ${table} AS target`,
+      `USING (VALUES (${valueParams})) AS source (${sourceColumns})`,
+      `ON ${joinCondition}`,
+      `WHEN MATCHED THEN UPDATE SET ${updateSet}`,
+      `WHEN NOT MATCHED THEN INSERT (${insertColumns}) VALUES (${insertValues});`
+    ].join(' ')
+
+    return {
+      sql,
+      nextParamIndex: startParamIndex + allColumns.length
+    }
+  }
+
+  paginate(params: {
+    sql: string
+    limit: number
+    offset?: number
+    paramIndex: number
+  }): { sql: string; nextParamIndex: number } {
+    const { sql, limit, offset, paramIndex } = params
+
+    if (offset !== undefined) {
+      return {
+        sql: `${sql} OFFSET @p${paramIndex} ROWS FETCH NEXT @p${paramIndex + 1} ROWS ONLY`,
+        nextParamIndex: paramIndex + 2
+      }
+    }
+
+    return {
+      sql: `${sql} OFFSET 0 ROWS FETCH NEXT @p${paramIndex} ROWS ONLY`,
+      nextParamIndex: paramIndex + 1
+    }
+  }
+
+  maxBatchRows(columnsPerRow: number): number {
+    return Math.floor(2000 / columnsPerRow)
+  }
+}

tests/unit/dialects/mysql-dialect.test.ts

@@ -0,0 +1,143 @@
+/**
+ * Unit tests for MySqlDialect
+ */
+
+import { describe, it, expect } from 'vitest'
+import { MySqlDialect } from '@services/database/dialects/mysql-dialect'
+
+describe('MySqlDialect', () => {
+  const dialect = new MySqlDialect()
+
+  describe('dbType', () => {
+    it('should return mysql', () => {
+      expect(dialect.dbType).toBe('mysql')
+    })
+  })
+
+  describe('quoteTableName', () => {
+    it('should join schema and table with underscore', () => {
+      expect(dialect.quoteTableName('dbo', 'Table')).toBe('dbo_Table')
+    })
+
+    it('should handle arbitrary schema and table names', () => {
+      expect(dialect.quoteTableName('my_schema', 'my_table')).toBe(
+        'my_schema_my_table'
+      )
+    })
+  })
+
+  describe('param', () => {
+    it('should return ? for any index', () => {
+      expect(dialect.param(0)).toBe('?')
+      expect(dialect.param(1)).toBe('?')
+      expect(dialect.param(5)).toBe('?')
+      expect(dialect.param(100)).toBe('?')
+    })
+  })
+
+  describe('params', () => {
+    it('should return comma-separated question marks', () => {
+      expect(dialect.params(1)).toBe('?')
+      expect(dialect.params(3)).toBe('?,?,?')
+      expect(dialect.params(5)).toBe('?,?,?,?,?')
+    })
+
+    it('should return empty string for count 0', () => {
+      expect(dialect.params(0)).toBe('')
+    })
+  })
+
+  describe('currentTimestamp', () => {
+    it('should return NOW()', () => {
+      expect(dialect.currentTimestamp()).toBe('NOW()')
+    })
+  })
+
+  describe('upsert', () => {
+    it('should generate ON DUPLICATE KEY UPDATE SQL', () => {
+      const result = dialect.upsert({
+        table: 'dbo_Table',
+        keyColumns: ['id'],
+        allColumns: ['id', 'name', 'value'],
+        startParamIndex: 0
+      })
+
+      expect(result.sql).toBe(
+        'INSERT INTO dbo_Table (id, name, value) VALUES (?, ?, ?) ON DUPLICATE KEY UPDATE name = VALUES(name), value = VALUES(value)'
+      )
+      expect(result.nextParamIndex).toBe(3)
+    })
+
+    it('should handle composite key columns', () => {
+      const result = dialect.upsert({
+        table: 'dbo_Table',
+        keyColumns: ['id', 'code'],
+        allColumns: ['id', 'code', 'name', 'value'],
+        startParamIndex: 0
+      })
+
+      expect(result.sql).toContain('ON DUPLICATE KEY UPDATE')
+      expect(result.sql).toContain('name = VALUES(name)')
+      expect(result.sql).toContain('value = VALUES(value)')
+      // key columns should NOT appear in the UPDATE SET clause
+      expect(result.sql).not.toContain('id = VALUES(id)')
+      expect(result.sql).not.toContain('code = VALUES(code)')
+      expect(result.nextParamIndex).toBe(4)
+    })
+
+    it('should advance nextParamIndex from non-zero start', () => {
+      const result = dialect.upsert({
+        table: 'dbo_Table',
+        keyColumns: ['id'],
+        allColumns: ['id', 'name'],
+        startParamIndex: 5
+      })
+
+      expect(result.nextParamIndex).toBe(7)
+    })
+  })
+
+  describe('paginate', () => {
+    it('should append LIMIT and OFFSET with literal values', () => {
+      const result = dialect.paginate({
+        sql: 'SELECT * FROM dbo_Table',
+        limit: 10,
+        offset: 20,
+        paramIndex: 0
+      })
+
+      expect(result.sql).toBe('SELECT * FROM dbo_Table LIMIT 10 OFFSET 20')
+      expect(result.nextParamIndex).toBe(0)
+    })
+
+    it('should use 0 as default offset', () => {
+      const result = dialect.paginate({
+        sql: 'SELECT * FROM dbo_Table',
+        limit: 50,
+        paramIndex: 3
+      })
+
+      expect(result.sql).toBe('SELECT * FROM dbo_Table LIMIT 50 OFFSET 0')
+      expect(result.nextParamIndex).toBe(3)
+    })
+
+    it('should not change nextParamIndex (no params added)', () => {
+      const result = dialect.paginate({
+        sql: 'SELECT * FROM dbo_Table',
+        limit: 100,
+        offset: 50,
+        paramIndex: 10
+      })
+
+      expect(result.nextParamIndex).toBe(10)
+    })
+  })
+
+  describe('maxBatchRows', () => {
+    it('should return 1000 regardless of columns', () => {
+      expect(dialect.maxBatchRows(1)).toBe(1000)
+      expect(dialect.maxBatchRows(10)).toBe(1000)
+      expect(dialect.maxBatchRows(100)).toBe(1000)
+    })
+  })
+})

tests/unit/dialects/postgresql-dialect.test.ts

@@ -0,0 +1,147 @@
+/**
+ * Unit tests for PostgreSqlDialect
+ */
+
+import { describe, it, expect } from 'vitest'
+import { PostgreSqlDialect } from '@services/database/dialects/postgresql-dialect'
+
+describe('PostgreSqlDialect', () => {
+  const dialect = new PostgreSqlDialect()
+
+  describe('dbType', () => {
+    it('should return postgresql', () => {
+      expect(dialect.dbType).toBe('postgresql')
+    })
+  })
+
+  describe('quoteTableName', () => {
+    it('should wrap schema and table in double quotes', () => {
+      expect(dialect.quoteTableName('dbo', 'Table')).toBe('"dbo"."Table"')
+    })
+
+    it('should handle arbitrary names', () => {
+      expect(dialect.quoteTableName('my_schema', 'my_table')).toBe(
+        '"my_schema"."my_table"'
+      )
+    })
+  })
+
+  describe('param', () => {
+    it('should return $N with 1-based index ($1 for param(0))', () => {
+      expect(dialect.param(0)).toBe('$1')
+      expect(dialect.param(1)).toBe('$2')
+      expect(dialect.param(3)).toBe('$4')
+      expect(dialect.param(10)).toBe('$11')
+    })
+  })
+
+  describe('params', () => {
+    it('should return comma-separated $N placeholders (1-based)', () => {
+      expect(dialect.params(1)).toBe('$1')
+      expect(dialect.params(3)).toBe('$1,$2,$3')
+      expect(dialect.params(5)).toBe('$1,$2,$3,$4,$5')
+    })
+
+    it('should return empty string for count 0', () => {
+      expect(dialect.params(0)).toBe('')
+    })
+  })
+
+  describe('currentTimestamp', () => {
+    it('should return CURRENT_TIMESTAMP', () => {
+      expect(dialect.currentTimestamp()).toBe('CURRENT_TIMESTAMP')
+    })
+  })
+
+  describe('upsert', () => {
+    it('should generate ON CONFLICT DO UPDATE SQL', () => {
+      const result = dialect.upsert({
+        table: '"dbo"."Table"',
+        keyColumns: ['id'],
+        allColumns: ['id', 'name', 'value'],
+        startParamIndex: 0
+      })
+
+      expect(result.sql).toContain('INSERT INTO "dbo"."Table" (id, name, value)')
+      expect(result.sql).toContain('VALUES ($1, $2, $3)')
+      expect(result.sql).toContain('ON CONFLICT ("id")')
+      expect(result.sql).toContain('DO UPDATE SET')
+      expect(result.sql).toContain('"name" = EXCLUDED."name"')
+      expect(result.sql).toContain('"value" = EXCLUDED."value"')
+      // key column should NOT appear in DO UPDATE SET
+      expect(result.sql).not.toContain('"id" = EXCLUDED."id"')
+      expect(result.nextParamIndex).toBe(3)
+    })
+
+    it('should handle composite key columns with all double-quoted', () => {
+      const result = dialect.upsert({
+        table: '"dbo"."Table"',
+        keyColumns: ['id', 'code'],
+        allColumns: ['id', 'code', 'name'],
+        startParamIndex: 0
+      })
+
+      expect(result.sql).toContain('ON CONFLICT ("id", "code")')
+      expect(result.sql).toContain('"name" = EXCLUDED."name"')
+      expect(result.nextParamIndex).toBe(3)
+    })
+
+    it('should use startParamIndex for parameter numbering', () => {
+      const result = dialect.upsert({
+        table: '"dbo"."Table"',
+        keyColumns: ['id'],
+        allColumns: ['id', 'name'],
+        startParamIndex: 5
+      })
+
+      // startParamIndex=5 means $6, $7 (1-based: index+1)
+      expect(result.sql).toContain('$6')
+      expect(result.sql).toContain('$7')
+      expect(result.nextParamIndex).toBe(7)
+    })
+  })
+
+  describe('paginate', () => {
+    it('should append LIMIT and OFFSET with literal values', () => {
+      const result = dialect.paginate({
+        sql: 'SELECT * FROM "dbo"."Table"',
+        limit: 10,
+        offset: 20,
+        paramIndex: 0
+      })
+
+      expect(result.sql).toBe('SELECT * FROM "dbo"."Table" LIMIT 10 OFFSET 20')
+      expect(result.nextParamIndex).toBe(0)
+    })
+
+    it('should use 0 as default offset', () => {
+      const result = dialect.paginate({
+        sql: 'SELECT * FROM "dbo"."Table"',
+        limit: 50,
+        paramIndex: 3
+      })
+
+      expect(result.sql).toBe('SELECT * FROM "dbo"."Table" LIMIT 50 OFFSET 0')
+      expect(result.nextParamIndex).toBe(3)
+    })
+
+    it('should not change nextParamIndex (no params added)', () => {
+      const result = dialect.paginate({
+        sql: 'SELECT * FROM "dbo"."Table"',
+        limit: 100,
+        offset: 50,
+        paramIndex: 10
+      })
+
+      expect(result.nextParamIndex).toBe(10)
+    })
+  })
+
+  describe('maxBatchRows', () => {
+    it('should return 1000 regardless of columns', () => {
+      expect(dialect.maxBatchRows(1)).toBe(1000)
+      expect(dialect.maxBatchRows(10)).toBe(1000)
+      expect(dialect.maxBatchRows(100)).toBe(1000)
+    })
+  })
+})

tests/unit/dialects/sqlserver-dialect.test.ts

@@ -0,0 +1,166 @@
+/**
+ * Unit tests for SqlServerDialect
+ */
+
+import { describe, it, expect } from 'vitest'
+import { SqlServerDialect } from '@services/database/dialects/sqlserver-dialect'
+
+describe('SqlServerDialect', () => {
+  const dialect = new SqlServerDialect()
+
+  describe('dbType', () => {
+    it('should return sqlserver', () => {
+      expect(dialect.dbType).toBe('sqlserver')
+    })
+  })
+
+  describe('quoteTableName', () => {
+    it('should wrap schema and table in brackets', () => {
+      expect(dialect.quoteTableName('dbo', 'Table')).toBe('[dbo].[Table]')
+    })
+
+    it('should handle arbitrary names', () => {
+      expect(dialect.quoteTableName('my_schema', 'my_table')).toBe(
+        '[my_schema].[my_table]'
+      )
+    })
+  })
+
+  describe('param', () => {
+    it('should return @pN with 0-based index', () => {
+      expect(dialect.param(0)).toBe('@p0')
+      expect(dialect.param(1)).toBe('@p1')
+      expect(dialect.param(5)).toBe('@p5')
+    })
+  })
+
+  describe('params', () => {
+    it('should return comma-separated @pN placeholders', () => {
+      expect(dialect.params(1)).toBe('@p0')
+      expect(dialect.params(3)).toBe('@p0,@p1,@p2')
+      expect(dialect.params(5)).toBe('@p0,@p1,@p2,@p3,@p4')
+    })
+
+    it('should return empty string for count 0', () => {
+      expect(dialect.params(0)).toBe('')
+    })
+  })
+
+  describe('currentTimestamp', () => {
+    it('should return GETDATE()', () => {
+      expect(dialect.currentTimestamp()).toBe('GETDATE()')
+    })
+  })
+
+  describe('upsert', () => {
+    it('should generate MERGE SQL with single key column', () => {
+      const result = dialect.upsert({
+        table: '[dbo].[Table]',
+        keyColumns: ['id'],
+        allColumns: ['id', 'name', 'value'],
+        startParamIndex: 0
+      })
+
+      // Should contain MERGE ... USING ... ON ... WHEN MATCHED ... WHEN NOT MATCHED ...
+      expect(result.sql).toContain('MERGE [dbo].[Table] AS target')
+      expect(result.sql).toContain('USING (VALUES (@p0, @p1, @p2)) AS source (id, name, value)')
+      expect(result.sql).toContain('ON target.id = source.id')
+      expect(result.sql).toContain('WHEN MATCHED THEN UPDATE SET')
+      expect(result.sql).toContain('target.name = source.name')
+      expect(result.sql).toContain('target.value = source.value')
+      expect(result.sql).toContain('WHEN NOT MATCHED THEN INSERT (id, name, value)')
+      expect(result.sql).toContain('VALUES (source.id, source.name, source.value)')
+      expect(result.nextParamIndex).toBe(3)
+    })
+
+    it('should handle composite key columns', () => {
+      const result = dialect.upsert({
+        table: '[dbo].[Table]',
+        keyColumns: ['id', 'code'],
+        allColumns: ['id', 'code', 'name'],
+        startParamIndex: 0
+      })
+
+      expect(result.sql).toContain('ON target.id = source.id AND target.code = source.code')
+      // non-key columns in UPDATE SET
+      expect(result.sql).toContain('target.name = source.name')
+      // key columns should NOT be in UPDATE SET
+      expect(result.sql).not.toMatch(/UPDATE SET[\s\S]*target\.id = source\.id/)
+      expect(result.nextParamIndex).toBe(3)
+    })
+
+    it('should use startParamIndex for parameter names', () => {
+      const result = dialect.upsert({
+        table: '[dbo].[Table]',
+        keyColumns: ['id'],
+        allColumns: ['id', 'name'],
+        startParamIndex: 5
+      })
+
+      expect(result.sql).toContain('@p5')
+      expect(result.sql).toContain('@p6')
+      expect(result.nextParamIndex).toBe(7)
+    })
+  })
+
+  describe('paginate', () => {
+    it('should append OFFSET/FETCH with parameterized offset when offset is provided', () => {
+      const result = dialect.paginate({
+        sql: 'SELECT * FROM [dbo].[Table] ORDER BY id',
+        limit: 10,
+        offset: 20,
+        paramIndex: 0
+      })
+
+      expect(result.sql).toContain('OFFSET @p0 ROWS')
+      expect(result.sql).toContain('FETCH NEXT @p1 ROWS ONLY')
+      expect(result.nextParamIndex).toBe(2)
+    })
+
+    it('should use literal 0 offset when no offset is provided', () => {
+      const result = dialect.paginate({
+        sql: 'SELECT * FROM [dbo].[Table] ORDER BY id',
+        limit: 50,
+        paramIndex: 0
+      })
+
+      expect(result.sql).toContain('OFFSET 0 ROWS')
+      expect(result.sql).toContain('FETCH NEXT @p0 ROWS ONLY')
+      expect(result.nextParamIndex).toBe(1)
+    })
+
+    it('should advance paramIndex from non-zero start with offset', () => {
+      const result = dialect.paginate({
+        sql: 'SELECT * FROM [dbo].[Table] ORDER BY id',
+        limit: 10,
+        offset: 100,
+        paramIndex: 5
+      })
+
+      expect(result.sql).toContain('OFFSET @p5 ROWS')
+      expect(result.sql).toContain('FETCH NEXT @p6 ROWS ONLY')
+      expect(result.nextParamIndex).toBe(7)
+    })
+
+    it('should advance paramIndex from non-zero start without offset', () => {
+      const result = dialect.paginate({
+        sql: 'SELECT * FROM [dbo].[Table] ORDER BY id',
+        limit: 10,
+        paramIndex: 3
+      })
+
+      expect(result.sql).toContain('OFFSET 0 ROWS')
+      expect(result.sql).toContain('FETCH NEXT @p3 ROWS ONLY')
+      expect(result.nextParamIndex).toBe(4)
+    })
+  })
+
+  describe('maxBatchRows', () => {
+    it('should return floor(2000 / columnsPerRow)', () => {
+      expect(dialect.maxBatchRows(10)).toBe(200)
+      expect(dialect.maxBatchRows(28)).toBe(71)
+      expect(dialect.maxBatchRows(1)).toBe(2000)
+      expect(dialect.maxBatchRows(100)).toBe(20)
+    })
+  })
+})