MCP Database Integrations

Introduction to Model Context Protocol (MCP)

James Chapman

AI Curriculum Manager, DataCamp

Why Add a Database to the Timezone Server?

Query power: filter, search, and sort without loading the whole dataset
Scale: fast lookups with database indexes

Why Add a Database to the Timezone Server?

Query power: filter, search, and sort without loading the whole dataset
Scale: fast lookups with database indexes
Concurrency: multiple tool calls or clients hit the DB safely
Production-ready: backups, replication, and a single source of truth

Data Access: Tools vs. Resources

Dynamic, heavily user-input dependent, writing operations
Examples: Data analytics and operations

Read-only, static data, reference information
Examples: Guidelines, docs, policies

Connection Lifecycle

Database Resource: timezone_server.py

from mcp.server.fastmcp import FastMCP
import sqlite3

mcp = FastMCP("Timezone Converter")

# Create connection at startup; reuse in handlers
conn = sqlite3.connect("timezones.db")
conn.row_factory = sqlite3.Row

@mcp.resource("db://timezones")
def get_locations() -> str:
    try:
        cursor = conn.execute("SELECT timezone FROM locations")
        rows = cursor.fetchall()
        return "\n".join(r["timezone"] for r in rows)
    except sqlite3.Error as e: return f"Error: {e}"

Database Lookup Tool: timezone_server.py

@mcp.tool()
def lookup_locations(prefix: str) -> str:
    """Find timezones that contain the given prefix."""
    try:
        cursor = conn.execute(
            "SELECT timezone FROM locations WHERE timezone LIKE ? LIMIT 50", (f"%{prefix}%",))
        rows = cursor.fetchall()
        return "\n".join(r["timezone"] for r in rows)
    except sqlite3.Error as e: return f"Error: {e}"


if __name__ == "__main__":
    try:
        mcp.run(transport="stdio")
    finally:
        conn.close()

Safety and Production Habits

Parameterized (?) queries: never string-format user or LLM input into SQL
- Prompt injection → malicious injection of code through prompts

SELECT timezone FROM locations WHERE timezone LIKE ? LIMIT 50

Prefer read-only and tightly scoped database access for the MCP server
Apply limits: max rows and timeouts

Let's practice!

Introduction to Model Context Protocol (MCP)