MySQLPool

A MySQL connection pool solution designed specifically for Nodejs, featuring intuitive chaining syntax that integrates query builder capabilities with read-write separation.

Features

• Dual Connection Pools: Separate read and write database connections
• Query Builder: Fluent interface for building SQL queries
• Environment Configuration: Easy setup using environment variables
• Connection Management: Automatic connection pooling and cleanup
• Slow Query Detection: Automatic logging of queries taking over 20ms
• JOIN Operations: Support for INNER, LEFT, and RIGHT joins
• CRUD Operations: Complete Create, Read, Update, Delete functionality
• UPSERT Support: Insert or update on duplicate key

Installation

npm install @pardnchiu/mysql-pool

Environment Configuration

Set up your database connections using environment variables:

Read Database (Optional)

DB_READ_HOST=localhost
DB_READ_PORT=3306
DB_READ_USER=read_user
DB_READ_PASSWORD=read_password
DB_READ_DATABASE=your_database
DB_READ_CHARSET=utf8mb4
DB_READ_CONNECTION=8

Write Database (Required for write operations)

DB_WRITE_HOST=localhost
DB_WRITE_PORT=3306
DB_WRITE_USER=write_user
DB_WRITE_PASSWORD=write_password
DB_WRITE_DATABASE=your_database
DB_WRITE_CHARSET=utf8mb4
DB_WRITE_CONNECTION=4

Quick Start

import MySQLPool from "@pardnchiu/mysql-pool";

// init pool
await MySQLPool.init();

// simple query
const users = await MySQLPool
  .table("users")
  .where("status", "active")
  .get();

// Close connections when done
await MySQLPool.close();

API Reference

Initialization

init(): Promise<void>

Initialize the database connection pools.

await MySQLPool.init();

close(): Promise<void>

Close all database connections.

await MySQLPool.close();

Query Builder Methods

table(tableName: string, target?: "read" | "write"): MySQLPool

Set the target table and target pool

MySQLPool.table("users");           // use read pool
MySQLPool.table("users", "write");  // use write pool

select(...fields: string[]): MySQLPool

Specify columns to select.

MySQLPool.table("users").select("id", "name", "email");
MySQLPool.table("users").select("COUNT(*) as total");

where(column: string, operator: any, value?: any): MySQLPool

Add WHERE conditions.

// Basic where
MySQLPool.table("users").where("id", 1);
MySQLPool.table("users").where("age", ">", 18);

// LIKE operator (automatically adds % wildcards)
MySQLPool.table("users").where('name', "LIKE", "John");

// IN operator
MySQLPool.table("users").where("id", "IN", [1, 2, 3]);

JOIN Operations

// INNER JOIN
MySQLPool.table("users")
  .innerJoin("profiles", "users.id", "profiles.user_id");

// LEFT JOIN
MySQLPool.table("users")
  .leftJoin("orders", "users.id", "orders.user_id");

// RIGHT JOIN with custom operator
MySQLPool.table("users")
  .rightJoin("posts", "users.id", "!=", "posts.author_id");

orderBy(column: string, direction?: "ASC" | "DESC"): MySQLPool

Add ORDER BY clause.

MySQLPool.table("users").orderBy("created_at", "DESC");
MySQLPool.table("users").orderBy("name"); // Defaults to ASC

limit(num: number): MySQLPool

Limit the number of results.

MySQLPool.table("users").limit(10);

offset(num: number): MySQLPool

Skip a number of records.

MySQLPool.table("users").offset(20).limit(10); // Pagination

total(): MySQLPool

Include total count in results (adds COUNT(*) OVER()).

const results = await MySQLPool
  .table("users")
  .total()
  .limit(10)
  .get();
// Results will include 'total' field with complete count

Data Operations

get<T>(): Promise<T[]>

Execute SELECT query and return results.

const users = await MySQLPool
  .table("users")
  .where("status", "active")
  .orderBy("created_at", "DESC")
  .get();

insert(data: Record<string, any>): Promise<number | null>

Insert a new record.

const userId = await MySQLPool
  .table("users")
  .insert({
    name: "John Doe",
    email: "john@example.com",
    created_at: "NOW()"
  });

update(data?: Record<string, any>): Promise<ResultSetHeader>

Update existing records.

// Update with data
const result = await MySQLPool
  .table("users")
  .where("id", 1)
  .update({
    name: "Jane Doe",
    updated_at: "NOW()"
  });

// Update using increase() method
await MySQLPool
  .table("users")
  .where("id", 1)
  .increase("login_count", 1)
  .update();

upsert(data: Record<string, any>, updateData?: Record<string, any> | string): Promise<number | null>

Insert or update on duplicate key.

// Simple upsert (updates all fields)
const id = await MySQLPool
  .table("users")
  .upsert({
    email: "john@example.com",
    name: "John Doe",
    login_count: 1
  });

// Upsert with specific update data
const id2 = await MySQLPool
  .table("users")
  .upsert(
    { email: "john@example.com", name: "John Doe", login_count: 1 },
    { updated_at: "NOW()" }
  );

Raw Queries

read<T>(query: string, params?: any[]): Promise<T>

Execute read query using read pool.

const users = await MySQLPool.read(`
SELECT COUNT(*) as total 
FROM users 
WHERE status = ?
`, ['active']);

write<T>(query: string, params?: any[]): Promise<T>

Execute write query using write pool.

const result = await MySQLPool.write(`
UPDATE users 
SET last_login = NOW() 
WHERE id = ?
`, [userId]);

Advanced Examples

Complex Query with Joins and Conditions

const reports = await MySQLPool
  .table("orders")
  .select("orders.id", "users.name", "products.title", "orders.total")
  .innerJoin("users", "orders.user_id", "users.id")
  .leftJoin("order_items", "orders.id", "order_items.order_id")
  .leftJoin("products", "order_items.product_id", "products.id")
  .where("orders.status", "completed")
  .where("orders.created_at", ">", "2023-01-01")
  .orderBy("orders.created_at", "DESC")
  .limit(50)
  .get();

Pagination with Total Count

const page = 1;
const perPage = 10;

const results = await MySQLPool
  .table("users")
  .select("id", "name", "email", "created_at")
  .where("status", "active")
  .total()
  .orderBy("created_at", "DESC")
  .limit(perPage)
  .offset((page - 1) * perPage)
  .get();

console.log(`total: ${results[0]?.total || 0}`);
console.log(`page: ${page}`);

Transaction-like Operations

try {
  // Create user
  const userId = await MySQLPool
    .table("users", "write")
    .insert({
      name: "John Doe",
      email: "john@example.com"
    });

  // Create user profile
  await MySQLPool
    .table("profiles", "write")
    .insert({
      user_id: userId,
      bio: "Software Developer",
      avatar: "avatar.jpg"
    });

  console.log("created successfully");
} catch (error) {
  console.error("failed to create:", error);
}

Supported MySQL Functions

The following MySQL functions are supported in update operations:

• NOW()
• CURRENT_TIMESTAMP
• UUID()
• RAND()
• CURDATE()
• CURTIME()
• UNIX_TIMESTAMP()
• UTC_TIMESTAMP()
• SYSDATE()
• LOCALTIME()
• LOCALTIMESTAMP()
• PI()
• DATABASE()
• USER()
• VERSION()

Error Handling

try {
  await MySQLPool.init();
  
  const users = await MySQLPool
    .table("users")
    .where("invalid_column", "value")
    .get();
    
} catch (error) {
  console.error("error:", error.message);
} finally {
  await MySQLPool.close();
}

Performance Features

• Connection Pooling: Automatic connection reuse
• Slow Query Detection: Queries over 20ms are automatically logged
• Prepared Statements: All queries use parameterized statements to prevent SQL injection
• Connection Management: Automatic connection release after each query

License

This source code project is licensed under the MIT license.

Creator

邱敬幃 Pardn Chiu

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©️ 2025 邱敬幃 Pardn Chiu