【深入浅出Node.js系列十三】用Nodejs连接MySQL

1 node-mysql介绍

felixge/node-mysql是一个纯nodejs的用javascript实现的一个MySQL客户端程序。felixge/node-mysql封装了Nodejs对MySQL的基本操作，100% MIT公共许可证。

项目地址：https://github.com/felixge/node-mysql

2 建立MySQL测试库

本地创建MySQL测试库：nodejs

~ mysql -uroot -p
mysql> CREATE DATABASE nodejs;
mysql> SHOW DATABASES; +--------------------+
| Database | +--------------------+
| information_schema | | mysql | | nodejs | | performance_schema |
+--------------------+
4 rows in set (0.00 sec)

新建一个user表：

CREATE TABLE t_user( id INT PRIMARY KEY AUTO_INCREMENT, name VARCHAR(16) NOT NULL , create_date TIMESTAMP NULL DEFAULT now() )ENGINE=InnoDB DEFAULT CHARSET=utf8;

CREATE UNIQUE INDEX t_quiz_IDX_0 on t_user(name);

3 node-mysql安装

~ D:\workspace\javascript\nodejs-node-mysql>npm install mysql@2.0.0-alpha9
npm http GET https://registry.npmjs.org/mysql/2.0.0-alpha9
npm http 200 https://registry.npmjs.org/mysql/2.0.0-alpha9
npm http GET https://registry.npmjs.org/mysql/-/mysql-2.0.0-alpha9.tgz
npm http 200 https://registry.npmjs.org/mysql/-/mysql-2.0.0-alpha9.tgz
npm http GET https://registry.npmjs.org/require-all/0.0.3
npm http GET https://registry.npmjs.org/bignumber.js/1.0.1
npm http 304 https://registry.npmjs.org/require-all/0.0.3
npm http 304 https://registry.npmjs.org/bignumber.js/1.0.1
mysql@2.0.0-alpha9 node_modules\mysql
├── require-all@0.0.3
└── bignumber.js@1.0.1

创建node程序启动文件：app.js

~ vi app.js

var mysql = require('mysql');
var conn = mysql.createConnection({
    host: 'localhost',
    user: 'nodejs',
    password: 'nodejs',
    database:'nodejs',
    port: 3306
});
conn.connect();
conn.query('SELECT 1 + 1 AS solution', function(err, rows, fields) {
    if (err) throw err;
    console.log('The solution is: ', rows[0].solution);
});
conn.end();

运行node：

~ D:\workspace\javascript\nodejs-node-mysql>node app.js
The solution is:  2

这样我们就让Nodejs连接上了MySQL。

4 node-mysql使用

4.1 表增删改查

修改app.js

~ vi app.js

var mysql = require('mysql');
var conn = mysql.createConnection({
    host: 'localhost',
    user: 'nodejs',
    password: 'nodejs',
    database: 'nodejs',
    port: 3306
});
conn.connect();

var insertSQL = 'insert into t_user(name) values("conan"),("fens.me")';
var selectSQL = 'select * from t_user limit 10';
var deleteSQL = 'delete from t_user';
var updateSQL = 'update t_user set name="conan update" where name="conan"';

//delete
conn.query(deleteSQL, function (err0, res0) {
    if (err0) console.log(err0);
    console.log("DELETE Return ==> ");
    console.log(res0);

    //insert
    conn.query(insertSQL, function (err1, res1) {
        if (err1) console.log(err1);
        console.log("INSERT Return ==> ");
        console.log(res1);

        //query
        conn.query(selectSQL, function (err2, rows) {
            if (err2) console.log(err2);

            console.log("SELECT ==> ");
            for (var i in rows) {
                console.log(rows[i]);
            }

            //update
            conn.query(updateSQL, function (err3, res3) {
                if (err3) console.log(err3);
                console.log("UPDATE Return ==> ");
                console.log(res3);

                //query
                conn.query(selectSQL, function (err4, rows2) {
                    if (err4) console.log(err4);

                    console.log("SELECT ==> ");
                    for (var i in rows2) {
                        console.log(rows2[i]);
                    }
                });
            });
        });
    });
});

//conn.end();

由于node的异步的，上面是一个连续的操作，代码会被写的支离破碎。我们可以通过async库对上面代码进行封装，请参考文章：Nodejs异步流程控制Async

4.2 连接池配置

增加文件：app-pooling.js

~ vi app-pooling.js

var mysql = require('mysql');
var pool = mysql.createPool({
    host: 'localhost',
    user: 'nodejs',
    password: 'nodejs',
    database: 'nodejs',
    port: 3306
});

var selectSQL = 'select * from t_user limit 10';

pool.getConnection(function (err, conn) {
    if (err) console.log("POOL ==> " + err);

    conn.query(selectSQL,function(err,rows){
        if (err) console.log(err);
        console.log("SELECT ==> ");
        for (var i in rows) {
            console.log(rows[i]);
        }
        conn.release();
    });
});

控制台输出：

D:\workspace\javascript\nodejs-node-mysql>node app-pooling.js
SELECT ==>
{ id: 39,
 name: 'conan update',
 create_date: Wed Sep 11 2013 13:41:18 GMT+0800 (中国标准时间) }
{ id: 40,
 name: 'fens.me',
 create_date: Wed Sep 11 2013 13:41:18 GMT+0800 (中国标准时间) }

4.3 MySQL断线重连

~ vi app-reconnect.js

var mysql = require('mysql');
var conn;
function handleError () {
    conn = mysql.createConnection({
        host: 'localhost',
        user: 'nodejs',
        password: 'nodejs',
        database: 'nodejs',
        port: 3306
    });

    //连接错误，2秒重试
    conn.connect(function (err) {
        if (err) {
            console.log('error when connecting to db:', err);
            setTimeout(handleError , 2000);
        }
    });

    conn.on('error', function (err) {
        console.log('db error', err);
        // 如果是连接断开，自动重新连接
        if (err.code === 'PROTOCOL_CONNECTION_LOST') {
            handleError();
        } else {
            throw err;
        }
    });
}
handleError();

function query(){
    console.log(new Date());
    var sql = "show variables like 'wait_timeout'";
    conn.query(sql, function (err, res) {
        console.log(res);
    });
}

query();
setInterval(query, 15*1000);

4.4 MySQL连接池的超时测试

针对wait_timeout问题，我们再对连接做一下测试。修改app-pooling.js文件：

var mysql = require('mysql');
var pool = mysql.createPool({
    host: 'localhost',
    user: 'nodejs',
    password: 'nodejs',
    database: 'nodejs',
    port: 3306
});

var selectSQL ="show variables like 'wait_timeout'";

pool.getConnection(function (err, conn) {
    if (err) console.log("POOL ==> " + err);

    function query(){
        conn.query(selectSQL, function (err, res) {
            console.log(new Date());
            console.log(res);
            conn.release();
        });
    }
    query();
    setInterval(query, 5000);
});

控制台输出：

D:\workspace\javascript\nodejs-node-mysql>node app-pooling.js
Wed Sep 11 2013 15:32:25 GMT+0800 (中国标准时间)
[ { Variable_name: 'wait_timeout', Value: '10' } ]
Wed Sep 11 2013 15:32:30 GMT+0800 (中国标准时间)
[ { Variable_name: 'wait_timeout', Value: '10' } ]
Wed Sep 11 2013 15:32:35 GMT+0800 (中国标准时间)
[ { Variable_name: 'wait_timeout', Value: '10' } ]

连接池，已经解决了自动重连的问题了，后面我们的开发，可以尽量使用pooling的方式。