對(duì)于node設(shè)置mysql數(shù)據(jù)庫示例代碼分享

本文實(shí)例講述了node操作mysql數(shù)據(jù)庫的方法。分享給大家供大家參考，具體如下：

1、建立數(shù)據(jù)庫連接：createConnection(Object)方法

該方法接受一個(gè)對(duì)象作為參數(shù)，該對(duì)象有四個(gè)常用的屬性host，user，password，database。與php中鏈接數(shù)據(jù)庫的參數(shù)相同。屬性列表如下：

還可以使用字符串連接數(shù)據(jù)庫例如：

var connection = mysql.createConnection('mysql://user:pass@host/db?debug=true&charset=BIG5_CHINESE_CI&timezone=-0700');

2、結(jié)束數(shù)據(jù)庫連接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)。

3、創(chuàng)建連接池 createPool(Object) Object和createConnection參數(shù)相同。

可以監(jiān)聽connection事件，并設(shè)置session值

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()

pool除了接受和connection相同的參數(shù)外，還接受幾個(gè)擴(kuò)展的參數(shù)

4、連接池集群

允許不同的host鏈接

// 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)

5、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)

6、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();

7、轉(zhuǎn)義查詢值

為了避免SQL注入攻擊，需要轉(zhuǎn)義用戶提交的數(shù)據(jù)。可以使用connection.escape() 或者 pool.escape()

例如：

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'

或者手動(dòng)轉(zhuǎn)換

var query = "SELECT * FROM posts WHERE title=" + mysql.escape("Hello MySQL");
console.log(query); // SELECT * FROM posts WHERE title='Hello MySQL'

8、轉(zhuǎn)換查詢標(biāo)識(shí)符

如果不能信任SQL標(biāo)識(shí)符(數(shù)據(jù)庫名、表名、列名)，可以使用轉(zhuǎn)換方法mysql.escapeId(identifier)；

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

9、準(zhǔn)備查詢

可以使用mysql.format來準(zhǔn)備查詢語句，該函數(shù)會(huì)自動(dòng)的選擇合適的方法轉(zhuǎn)義參數(shù)。

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" });

11、獲取插入行的id

當(dāng)使用自增主鍵時(shí)獲取插入行id，如：

connection.query('INSERT INTO posts SET ?', {title: 'test'}, function(err, result) {
   if (err) throw err;
   console.log(result.insertId);
  });

12、流處理

有時(shí)你希望選擇大量的行并且希望在數(shù)據(jù)到達(dá)時(shí)就處理他們，你就可以使用這個(gè)方法

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
   });

13、混合查詢語句（多語句查詢）

因?yàn)榛旌喜樵內(nèi)菀妆籗QL注入攻擊，默認(rèn)是不允許的，可以使用：

var connection = mysql.createConnection({multipleStatements: true});

開啟該功能。

混合查詢實(shí)例：

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)查詢語句出錯(cuò)，Error對(duì)象會(huì)包含err.index指示錯(cuò)誤語句的id，整個(gè)查詢也會(huì)終止。

混合查詢結(jié)果的流處理方式是做實(shí)驗(yàn)性的，不穩(wěn)定。

14、事務(wù)處理

connection級(jí)別的簡單事務(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!');
     });
    });
   });
  });

15、錯(cuò)誤處理

err.code = string
err.fatal => boolean

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