@pilat/mcp-datalink
MCP server for PostgreSQL, MySQL, and SQLite. Gives AI assistants secure database access via Model Context Protocol.
npx @pilat/mcp-datalink
Works with Claude Desktop, Claude Code, Cursor, Cline, and any MCP-compatible client.
Installation
Add to your MCP client config file (see config locations below):
{
"mcpServers": {
"datalink": {
"command": "npx",
"args": ["-y", "@pilat/mcp-datalink"],
"env": {
"DATALINK_ANALYTICS_URL": "postgresql://user:password@localhost:5432/analytics",
"DATALINK_ANALYTICS_READONLY": "true",
"DATALINK_INVENTORY_URL": "mysql://user:password@localhost:3306/inventory",
"DATALINK_CACHE_URL": "sqlite:///path/to/cache.db"
}
}
}
}
This creates three database connections: analytics (read-only), inventory, and cache.
| Variable | Description |
|---|---|
DATALINK_{NAME}_URL | Connection URL (creates database named {name}) |
DATALINK_{NAME}_READONLY | Set to true to block writes |
DATALINK_{NAME}_MAX_TIMEOUT | Max query timeout in ms (caps model requests) |
Connection URL formats:
# PostgreSQL
postgresql://user:password@localhost:5432/dbname
postgresql://user:password@localhost:5432/dbname?sslmode=require
# MySQL
mysql://user:password@localhost:3306/dbname
mysql://user:password@localhost:3306/dbname?ssl=true
# SQLite
sqlite:///path/to/database.db
sqlite:///Users/me/data/app.sqlite
sqlite://../relative/path/data.db
Environment Variable Substitution
URLs support ${VAR} syntax to reference other environment variables:
{
"mcpServers": {
"datalink": {
"command": "npx",
"args": ["-y", "@pilat/mcp-datalink"],
"env": {
"DATALINK_MAIN_URL": "${DATABASE_URL}"
}
}
}
}
This allows reusing existing environment variables (like DATABASE_URL from your shell or .env file).
Supported syntax:
| Syntax | Description |
|---|---|
${VAR} | Expands to value of VAR, or keeps ${VAR} if unset |
${VAR:-default} | Expands to value of VAR, or default if unset |
Examples:
# Reference existing DATABASE_URL
DATALINK_MAIN_URL="${DATABASE_URL}"
# Build URL from parts
DATALINK_MAIN_URL="postgresql://${DB_USER}:${DB_PASS}@${DB_HOST}:5432/mydb"
# With default values
DATALINK_MAIN_URL="postgresql://localhost:${DB_PORT:-5432}/mydb"
Config File Locations
| Client | Config file |
|---|---|
| Claude Code | ~/.claude.json (global) or .mcp.json (project) |
| Claude Desktop (macOS) | ~/Library/Application Support/Claude/claude_desktop_config.json |
| Claude Desktop (Windows) | %APPDATA%\Claude\claude_desktop_config.json |
| Cursor | ~/.cursor/mcp.json or Settings → Features → MCP Servers |
| Cline | cline_mcp_settings.json or VS Code settings cline.mcpServers |
Tools
| Tool | Description |
|---|---|
list_databases | List configured database connections |
list_tables | List tables with row counts |
describe_table | Get schema, indexes, foreign keys |
query | Run SELECT queries |
execute | Run INSERT/UPDATE/DELETE |
explain | Show query execution plans |
Security
- Prepared statements only (no SQL injection)
- Single statement per query (no chaining)
- DDL blocked (no DROP, ALTER, TRUNCATE)
- Readonly mode per connection
- Response size limit (100 rows, 64KB default, configurable via
DATALINK_MAX_TOTAL_SIZE) - Query timeout: 30s default, model can request up to 10min,
MAX_TIMEOUTcaps it
License
MIT