Add SQL connector with multi-flavor and multi-database access support (MySQL, PostgreSQL, SQLite, MSSQL)

[Copilot]

Implements a universal SQL database connector supporting MySQL, PostgreSQL, SQLite, and Microsoft SQL Server through a unified interface with multi-database access capabilities.

Core Implementation

Client Factory Pattern (connections/sql/src/lib.ts)

• Unified SQLClient interface abstracts database-specific implementations
• Automatic parameter placeholder conversion: ? → $1, $2... (PostgreSQL), @param0, @param1... (MSSQL)
• Per-flavor result normalization (e.g., changes for SQLite, rowCount for PostgreSQL)
• Shared utilities for database switching and identifier validation

Tools (connections/sql/src/queries/)

• listDatabases: Lists all databases available on the server with appropriate permissions
• switchDatabase: Switches between databases at runtime (MySQL, MSSQL)
• executeQuery: Parameterized query execution with SQL injection protection and optional per-query database selection
• listTables: Flavor-aware table enumeration with optional database parameter
• describeTable: Schema introspection with optional database parameter

Multi-Database Access

The connector now supports accessing multiple databases on a single server connection:

• Database Discovery: List all databases the user has permissions to access
• Runtime Switching: Switch between databases during execution (MySQL, MSSQL)
• Per-Query Selection: Specify target database for individual operations
• Server-Level Connections: Optional database parameter allows connection at server level

Support by Flavor:

• MySQL: ✅ List, switch, and per-query database selection
• MSSQL: ✅ List, switch, and per-query database selection
• PostgreSQL: ✅ List databases (connections are database-specific)
• SQLite: ⚠️ File-based, single database per connection

Configuration

Supports flavor-specific connection parameters:

// MySQL/PostgreSQL/MSSQL - database parameter now optional for server-level access
{ flavor: "mysql", host: "localhost", port: 3306, username: "user", password: "pass" }
{ flavor: "postgresql", host: "localhost", port: 5432, database: "mydb", username: "user", password: "pass" }

// SQLite
{ flavor: "sqlite", filePath: "/path/to/db.sqlite" }

Security

• Database identifier validation to prevent SQL injection
• Proper identifier quoting (backticks for MySQL, brackets for MSSQL)
• Parameterized queries with automatic placeholder conversion

Integration

• Registered in server/src/lib/connection.ts alongside existing connectors
• Dependencies: mysql2, pg, better-sqlite3, mssql

Original prompt

implement an SQL connector that can connect to mySQL postgres and all of the other flavors of SQL database

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[danhab99]

I would like for it to have access to all of the databases available in the server given permissions

[Copilot]

I would like for it to have access to all of the databases available in the server given permissions

Done! The SQL connector now supports multi-database access with these new capabilities:

New Tools:

• listDatabases - Lists all databases on the server
• switchDatabase - Switches between databases (MySQL/MSSQL)

Enhanced Tools:

• executeQuery, listTables, describeTable now accept optional database parameter for per-query database selection

Security:

• Database identifiers are validated to prevent SQL injection
• Proper quoting for MySQL (backticks) and MSSQL (brackets)

The connector can now access all databases on the server given appropriate permissions. Implementation in commits b5977cf and b230cd8.