MCP Server MySQL

Instructions

Implementation Reference

• src/index.ts:362-405 (handler)

  The handler function for the 'alter_table' tool. It constructs and executes an ALTER TABLE SQL statement based on the operation (ADD, DROP, MODIFY, RENAME) using the provided parameters, then returns a success response with structured output.

  async ({ table, operation, column, definition, newName, database }) => {
    const p = await getPool();
  
    const tableName = database ? `\`${database}\`.\`${table}\`` : `\`${table}\``;
    let sql: string;
  
    switch (operation) {
      case "ADD":
        sql = `ALTER TABLE ${tableName} ADD COLUMN \`${column}\` ${definition}`;
        break;
      case "DROP":
        sql = `ALTER TABLE ${tableName} DROP COLUMN \`${column}\``;
        break;
      case "MODIFY":
        sql = `ALTER TABLE ${tableName} MODIFY COLUMN \`${column}\` ${definition}`;
        break;
      case "RENAME":
        sql = `ALTER TABLE ${tableName} RENAME COLUMN \`${column}\` TO \`${newName}\``;
        break;
      default:
        throw new Error(`Unknown operation: ${operation}`);
    }
  
    await p.execute(sql);
  
    const output = {
      success: true,
      table,
      operation,
      column,
      newName: newName || null,
      database: database || null,
    };
  
    return {
      content: [
        {
          type: "text" as const,
          text: `Table ${table} altered successfully (${operation} ${column})`,
        },
      ],
      structuredContent: output,
    };
  }

• src/index.ts:354-361 (schema)

  Zod schema defining the input parameters for the 'alter_table' tool: table, operation (enum), column, optional definition, newName, and database.

  {
    table: z.string().describe("Table name"),
    operation: z.enum(["ADD", "DROP", "MODIFY", "RENAME"]).describe("Type of alteration"),
    column: z.string().describe("Column name"),
    definition: z.string().optional().describe("Column definition for ADD/MODIFY (e.g., 'VARCHAR(255) NOT NULL')"),
    newName: z.string().optional().describe("New name for RENAME operation"),
    database: z.string().optional().describe("Database name (optional)"),
  },

• src/index.ts:351-406 (registration)

  Registration of the 'alter_table' tool using server.tool(), including name, description, input schema, and inline handler function.

  server.tool(
    "alter_table",
    "Modify an existing table structure",
    {
      table: z.string().describe("Table name"),
      operation: z.enum(["ADD", "DROP", "MODIFY", "RENAME"]).describe("Type of alteration"),
      column: z.string().describe("Column name"),
      definition: z.string().optional().describe("Column definition for ADD/MODIFY (e.g., 'VARCHAR(255) NOT NULL')"),
      newName: z.string().optional().describe("New name for RENAME operation"),
      database: z.string().optional().describe("Database name (optional)"),
    },
    async ({ table, operation, column, definition, newName, database }) => {
      const p = await getPool();
  
      const tableName = database ? `\`${database}\`.\`${table}\`` : `\`${table}\``;
      let sql: string;
  
      switch (operation) {
        case "ADD":
          sql = `ALTER TABLE ${tableName} ADD COLUMN \`${column}\` ${definition}`;
          break;
        case "DROP":
          sql = `ALTER TABLE ${tableName} DROP COLUMN \`${column}\``;
          break;
        case "MODIFY":
          sql = `ALTER TABLE ${tableName} MODIFY COLUMN \`${column}\` ${definition}`;
          break;
        case "RENAME":
          sql = `ALTER TABLE ${tableName} RENAME COLUMN \`${column}\` TO \`${newName}\``;
          break;
        default:
          throw new Error(`Unknown operation: ${operation}`);
      }
  
      await p.execute(sql);
  
      const output = {
        success: true,
        table,
        operation,
        column,
        newName: newName || null,
        database: database || null,
      };
  
      return {
        content: [
          {
            type: "text" as const,
            text: `Table ${table} altered successfully (${operation} ${column})`,
          },
        ],
        structuredContent: output,
      };
    }
  );