nodejs 简单连接msql

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();

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();

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();
});
});

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();

mysql> show variables like 'wait_timeout';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wait_timeout  | 28800 |
+---------------+-------+
1 row in set (0.00 sec)

mysql> set global wait_timeout=10;
Query OK, 0 rows affected (0.00 sec)

mysql> show variables like 'wait_timeout';
+---------------+-------+
| Variable_name | Value |
+---------------+-------+
| wait_timeout  | 10    |
+---------------+-------+
1 row in set (0.00 sec)

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);

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);
});