浅析php+mysql怎么实现读写分离

SELECT * FROM users WHERE age>18;

//生成一个读取从库的连接
$slaveConn = mysqli_connect($slaveHost, $slaveUser, $slavePass, $dbName);
mysqli_query($slaveConn, "SET NAMES utf8");

//查询数据
$result = mysqli_query($slaveConn, "SELECT * FROM users WHERE age>18");

INSERT INTO users (name,age,sex) VALUES ('jack',18,'male');

//生成一个写入主库的连接
$masterConn = mysqli_connect($masterHost, $masterUser, $masterPass, $dbName);
mysqli_query($masterConn, "SET NAMES utf8");

//插入数据
$result = mysqli_query($masterConn, "INSERT INTO users (name,age,sex) VALUES ('jack',18,'male')");

//生成一个读取从库的连接
$slaveConn = Yii::$app->slaveDb->getConnection();

//查询数据
$query = new \yii\db\Query();
$result = $query->from('users')->where(['age' > 18])->all($slaveConn);

//生成一个写入主库的连接
$masterConn = Yii::$app->masterDb->getConnection();

//插入数据
$result = Yii::$app->db->createCommand()->insert('users', [
'name' => 'jack',
'age' => 18,
'sex' => 'male'
])->execute($masterConn);

//从库连接信息
$slave1 = array(
'host' => 'slave1.host.com', 
'user' => 'slave1user', 
'pass' => 'slave1pass',
'name' => 'dbname'
);

$slave2 = array(
'host' => 'slave2.host.com', 
'user' => 'slave2user', 
'pass' => 'slave2pass',
'name' => 'dbname'
);

$slave3 = array(
'host' => 'slave3.host.com', 
'user' => 'slave3user', 
'pass' => 'slave3pass',
'name' => 'dbname'
);


//增加从库列表
$slaveList = array($slave1, $slave2, $slave3);


//轮询获取从库连接信息
function getSlaveConn() {
global $slaveList;
static $index = 0;
if ($index >= count($slaveList)) {
    $index = 0;
}
$slave = $slaveList[$index];
$index++;
$conn = mysqli_connect($slave['host'], $slave['user'], $slave['pass'], $slave['name']);
mysqli_query($conn, "SET NAMES utf8");
return $conn;
}