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一、建立數(shù)據(jù)庫(kù)連接：createConnection(Object)方法
還可以使用字符串連接數(shù)據(jù)庫(kù)例如： 復(fù)制代碼 代碼如下: var connection = mysql.createConnection('mysql://user:pass@host/db?debug=true&charset=BIG5_CHINESE_CI&timezone=-0700'); 二、結(jié)束數(shù)據(jù)庫(kù)連接end()和destroy() end()接受一個(gè)回調(diào)函數(shù)，并且會(huì)在query結(jié)束之后才觸發(fā)，如果query出錯(cuò)，仍然會(huì)終止鏈接，錯(cuò)誤會(huì)傳遞到回調(diào)函數(shù)中處理。 destroy()立即終止數(shù)據(jù)庫(kù)連接，即使還有query沒有完成，之后的回調(diào)函數(shù)也不會(huì)在觸發(fā)。 三、創(chuàng)建連接池 createPool(Object) Object和createConnection參數(shù)相同。 pool.on('connection', function(connection) {
connection.query('SET SESSION auto_increment_increment=1')
});
connection.release()釋放鏈接到連接池。如果需要關(guān)閉連接并且刪除，需要使用connection.destroy() createConnection: 用于創(chuàng)建鏈接的函數(shù). (Default: mysql.createConnection) 四、連接池集群 // create
var poolCluster = mysql.createPoolCluster();
poolCluster.add(config); // anonymous group
poolCluster.add('MASTER', masterConfig);
poolCluster.add('SLAVE1', slave1Config);
poolCluster.add('SLAVE2', slave2Config);
// Target Group : ALL(anonymous, MASTER, SLAVE1-2), Selector : round-robin(default)
poolCluster.getConnection(function (err, connection) {});
// Target Group : MASTER, Selector : round-robin
poolCluster.getConnection('MASTER', function (err, connection) {});
// Target Group : SLAVE1-2, Selector : order
// If can't connect to SLAVE1, return SLAVE2. (remove SLAVE1 in the cluster)
poolCluster.on('remove', function (nodeId) {
console.log('REMOVED NODE : ' + nodeId); // nodeId = SLAVE1
});
poolCluster.getConnection('SLAVE*', 'ORDER', function (err, connection) {});
// of namespace : of(pattern, selector)
poolCluster.of('*').getConnection(function (err, connection) {});
var pool = poolCluster.of('SLAVE*', 'RANDOM');
pool.getConnection(function (err, connection) {});
pool.getConnection(function (err, connection) {});
// destroy
poolCluster.end();
鏈接集群的可選參數(shù) canRetry: 值為true時(shí)，允許連接失敗時(shí)重試(Default: true)
五、切換用戶/改變連接狀態(tài) Mysql允許在比斷開連接的的情況下切換用戶 connection.changeUser({user : 'john'}, function(err) {
if (err) throw err;
});
參數(shù)
六、處理服務(wù)器連接斷開 var db_config = {
host: 'localhost',
user: 'root',
password: '',
database: 'example'
};
var connection;
function handleDisconnect() {
connection = mysql.createConnection(db_config); // Recreate the connection, since
// the old one cannot be reused.
connection.connect(function(err) { // The server is either down
if(err) { // or restarting (takes a while sometimes).
console.log('error when connecting to db:', err);
setTimeout(handleDisconnect, 2000); // We introduce a delay before attempting to reconnect,
} // to avoid a hot loop, and to allow our node script to
}); // process asynchronous requests in the meantime.
// If you're also serving http, display a 503 error.
connection.on('error', function(err) {
console.log('db error', err);
if(err.code === 'PROTOCOL_CONNECTION_LOST') { // Connection to the MySQL server is usually
handleDisconnect(); // lost due to either server restart, or a
} else { // connnection idle timeout (the wait_timeout
throw err; // server variable configures this)
}
});
}
handleDisconnect();
七、轉(zhuǎn)義查詢值 var userId = 'some user provided value';
var sql = 'SELECT * FROM users WHERE id = ' + connection.escape(userId);
connection.query(sql, function(err, results) {
// ...
});
或者使用？作為占位符
connection.query('SELECT * FROM users WHERE id = ?', [userId], function(err, results) {
// ...
});
不同類型值的轉(zhuǎn)換結(jié)果
Numbers 不變
Booleans 轉(zhuǎn)換為字符串 'true' / 'false'
Date 對(duì)象轉(zhuǎn)換為字符串 'YYYY-mm-dd HH:ii:ss'
Buffers 轉(zhuǎn)換為是6進(jìn)制字符串
Strings 不變
Arrays => ['a', 'b'] 轉(zhuǎn)換為 'a', 'b'
嵌套數(shù)組 [['a', 'b'], ['c', 'd']] 轉(zhuǎn)換為 ('a', 'b'), ('c', 'd')
Objects 轉(zhuǎn)換為 key = 'val' pairs. 嵌套對(duì)象轉(zhuǎn)換為字符串.
undefined / null ===> NULL
NaN / Infinity 不變. MySQL 不支持這些值, 除非有工具支持，否則插入這些值會(huì)引起錯(cuò)誤.
轉(zhuǎn)換實(shí)例：
var post = {id: 1, title: 'Hello MySQL'};
var query = connection.query('INSERT INTO posts SET ?', post, function(err, result) {
// Neat!
});
console.log(query.sql); // INSERT INTO posts SET `id` = 1, `title` = 'Hello MySQL'
var query = "SELECT * FROM posts WHERE title=" + mysql.escape("Hello MySQL");
console.log(query); // SELECT * FROM posts WHERE title='Hello MySQL'
八、轉(zhuǎn)換查詢標(biāo)識(shí)符 var sorter = 'date';
var query = 'SELECT * FROM posts ORDER BY ' + mysql.escapeId(sorter);
console.log(query); // SELECT * FROM posts ORDER BY `date`
支持轉(zhuǎn)義多個(gè)
var sorter = 'date';
var query = 'SELECT * FROM posts ORDER BY ' + mysql.escapeId('posts.' + sorter);
console.log(query); // SELECT * FROM posts ORDER BY `posts`.`date`
可以使用??作為標(biāo)識(shí)符的占位符
var userId = 1;
var columns = ['username', 'email'];
var query = connection.query('SELECT ?? FROM ?? WHERE id = ?', [columns, 'users', userId], function(err, results) {
// ...
});
console.log(query.sql); // SELECT `username`, `email` FROM `users` WHERE id = 1
九、準(zhǔn)備查詢 var sql = "SELECT * FROM ?? WHERE ?? = ?";
var inserts = ['users', 'id', userId];
sql = mysql.format(sql, inserts);
10、自定義格式化函數(shù)
connection.config.queryFormat = function (query, values) {
if (!values) return query;
return query.replace(/\:(\w+)/g, function (txt, key) {
if (values.hasOwnProperty(key)) {
return this.escape(values[key]);
}
return txt;
}.bind(this));
};
connection.query("UPDATE posts SET title = :title", { title: "Hello MySQL" });
十、獲取插入行的id connection.query('INSERT INTO posts SET ?', {title: 'test'}, function(err, result) {
if (err) throw err;
console.log(result.insertId);
});
十一、流處理 var query = connection.query('SELECT * FROM posts');
query
.on('error', function(err) {
// Handle error, an 'end' event will be emitted after this as well
})
.on('fields', function(fields) {
// the field packets for the rows to follow
})
.on('result', function(row) {
// Pausing the connnection is useful if your processing involves I/O
connection.pause();
processRow(row, function() {
connection.resume();
});
})
.on('end', function() {
// all rows have been received
});
十二、混合查詢語(yǔ)句（多語(yǔ)句查詢） connection.query('SELECT 1; SELECT 2', function(err, results) {
if (err) throw err;
// `results` is an array with one element for every statement in the query:
console.log(results[0]); // [{1: 1}]
console.log(results[1]); // [{2: 2}]
});
同樣可以使用流處理混合查詢結(jié)果： var query = connection.query('SELECT 1; SELECT 2');
query
.on('fields', function(fields, index) {
// the fields for the result rows that follow
})
.on('result', function(row, index) {
// index refers to the statement this result belongs to (starts at 0)
});
如果其中一個(gè)查詢語(yǔ)句出錯(cuò)，Error對(duì)象會(huì)包含err.index指示錯(cuò)誤語(yǔ)句的id，整個(gè)查詢也會(huì)終止。 十三、事務(wù)處理 connection.beginTransaction(function(err) {
if (err) { throw err; }
connection.query('INSERT INTO posts SET title=?', title, function(err, result) {
if (err) {
connection.rollback(function() {
throw err;
});
}
var log = 'Post ' + result.insertId + ' added';
connection.query('INSERT INTO log SET data=?', log, function(err, result) {
if (err) {
connection.rollback(function() {
throw err;
});
}
connection.commit(function(err) {
if (err) {
connection.rollback(function() {
throw err;
});
}
console.log('success!');
});
});
});
});
十四、錯(cuò)誤處理 err.code = string err.fatal => boolean
想了很久也想不明白為神馬mysql模塊沒有執(zhí)行回調(diào)，最后突然想起來去看了下錯(cuò)誤日志，才發(fā)現(xiàn)有個(gè)“No reconnection after connection lost”錯(cuò)誤沒有被捕捉到，原來是連接丟失了，上github上看了下文檔和issues，上面說到連接丟失后不會(huì)自動(dòng)重新連接，會(huì)觸發(fā)error事件。我趕緊給程序添加了斷線后自動(dòng)重連功能，現(xiàn)在已正常運(yùn)行了10多天。 MySQL中有一個(gè)名叫wait_timeout的變量，表示操作超時(shí)時(shí)間，當(dāng)連接超過一定時(shí)間沒有活動(dòng)后，會(huì)自動(dòng)關(guān)閉該連接，這個(gè)值默認(rèn)為28800（即8小時(shí)）。 自動(dòng)重連數(shù)據(jù)庫(kù)的代碼： function handleError (err) {
if (err) {
// 如果是連接斷開，自動(dòng)重新連接
if (err.code === 'PROTOCOL_CONNECTION_LOST') {
connect();
} else {
console.error(err.stack || err);
}
}
}
// 連接數(shù)據(jù)庫(kù)
function connect () {
db = mysql.createConnection(config);
db.connect(handleError);
db.on('error', handleError);
}
var db;
connect();
網(wǎng)上流傳的大多數(shù)使用mysql模塊的代碼，往往忽略了這個(gè)問題，一不小心就讓一撥又一撥的人往坑里踩了。 var mysql = require('mysql');
var pool = mysql.createPool(config);
pool.getConnection(function(err, connection) {
// Use the connection
connection.query( 'SELECT something FROM sometable', function(err, rows) {
// And done with the connection.
connection.end();
// Don't use the connection here, it has been returned to the pool.
});
});
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