npm mysql study notes

The npm module mysql module is a module for operating the mysql database on the node side

Talking about trouble, it is still comprehensive on the official website

https://www.npmjs.com/package/mysql

Code directly

const config = {
    host: "localhost",
    port: "3306",
    user: "root",
    password: "root",
    database: "node_app"
};
module.exports = config;

const mysql = require("mysql");
const defaultConfig = require("./config");
 // 自己封装工具类
class ConnectionPool {
    constructor(config = {}) {
        this.pool = mysql.createPool({
            ...defaultConfig,
            ...config
        });
    }
    // 封装查询
    query(sql) {
        return new Promise((resolve, reject) => {
            this.pool.getConnection((err, connection) => {
                if (err) {
                    reject(err);
                } else {
                    connection.query(sql, (err2, rows) => {
                        if (err2) {
                            reject(err2);
                        } else {
                            resolve(rows);
                        }
                        connection.release();
                    });
                }
            });
        });
    }
    // 封装事务处理 
    transaction(sqlArr) {
        return new Promise((resolve, reject) => {
            this.pool.getConnection((err, connection) => {
                if (err) {
                    reject(err);
                } else {
                    connection.beginTransaction(err2 => {
                        if (err2) {
                            reject(err2);
                        } else {
                            this._queryTran(
                                connection,
                                0,
                                sqlArr,
                                resolve,
                                reject
                            );
                        }
                    });
                }
            });
        });
    }
    // 递归执行sql
    _queryTran(connection, index, arr, resolve, reject) {
        connection.query(arr[index], (err, row) => {
            if (err) {
                connection.rollback(err2 => {
                    if (err2) {
                        reject({ err, err2 });
                        connection.release();
                    } else {
                        reject(err);
                        connection.release();
                    }
                });
            } else if (index + 1 < arr.length) {
                this._queryTran(connection, index + 1, arr, resolve, reject);
            } else {
                connection.commit(err3 => {
                    if (err3) {
                        connection.rollback(err3 => {
                            if (err4) {
                                reject({ err3, err4 });
                                connection.release();
                            } else {
                                reject(err3);
                                connection.release();
                            }
                        });
                    } else {
                        resolve("success");
                        connection.release();
                    }
                });
            }
        });
    }
    // 关闭连接池
    end() {
        this.pool.end(err => {
            if (err) {
                console.error(err);
            }
        });
    }
}
module.exports = new ConnectionPool();

test

const Pool = require("./connection");
const pool = new Pool();
pool.query("select * from user")
    .then(rows => {
        console.log(rows);
    })
    .catch(err => {
        console.error(err);
	});
const arr = [
    "INSERT INTO `user` VALUES (null,'kim1',77,666,'hei')",
    "INSERT INTO `user` VALUES (null,'kim2',77,666,'hei')",
    "INSERT INTO `user` VALUES (1,'kim3',77,666,'hei')",
    "INSERT INTO `user` VALUES (null,'kim3',77,666,'hei')"
];

pool.transaction(arr)
    .then(res => {
        pool.end();
    })
    .catch(err => {
        console.error(err);
        pool.end();
    });