MySQL-workerman

###依赖的扩展
该mysql类依赖pdo和pdo_mysql两个扩展，缺少扩展会报Undefined class constant 'MYSQL_ATTR_INIT_COMMAND' in ....错误。
命令行运行`php -m`会列出所有php cli已安装的扩展，如果没有pdo 或者 pdo_mysql，请自行安装

###安装
    composer require workerman/mysql

###示例
    use Workerman\Worker;
    require_once __DIR__ . '/Workerman/Autoloader.php';
    require_once __DIR__ . '/vendor/autoload.php';
    
    $worker = new Worker('websocket://0.0.0.0:8484');
    $worker->onWorkerStart = function($worker)
    {
        // 将db实例存储在全局变量中(也可以存储在某类的静态成员中)
        global $db;
        $db = new \Workerman\MySQL\Connection('host', 'port', 'user', 'password', 'db_name');
    };
    $worker->onMessage = function($connection, $data)
    {
        // 通过全局变量获得db实例
        global $db;
        // 执行SQL
        $all_tables = $db->query('show tables');
        $connection->send(json_encode($all_tables));
    };
    // 运行worker
    Worker::runAll();

###具体MySQL用法
    // 初始化db连接
    $db = new \Workerman\MySQL\Connection('host', 'port', 'user', 'password', 'db_name');
    
    // 获取所有数据
    $db->select('ID,Sex')->from('Persons')->where('sex= :sex AND ID = :id')->bindValues(array('sex'=>'M', 'id' => 1))->query();
    //等价于
    $db->select('ID,Sex')->from('Persons')->where("sex= 'M' AND ID = 1")->query();
    //等价于
    $db->query("SELECT ID,Sex FROM `Persons` WHERE sex='M' AND ID = 1");
    
    
    // 获取一行数据
    $db->select('ID,Sex')->from('Persons')->where('sex= :sex')->bindValues(array('sex'=>'M'))->row();
    //等价于
    $db->select('ID,Sex')->from('Persons')->where("sex= 'M' ")->row();
    //等价于
    $db->row("SELECT ID,Sex FROM `Persons` WHERE sex='M'");
    
    
    // 获取一列数据
    $db->select('ID')->from('Persons')->where('sex= :sex')->bindValues(array('sex'=>'M'))->column();
    //等价于
    $db->select('ID')->from('Persons')->where("sex= 'F' ")->column();
    //等价于
    $db->column("SELECT `ID` FROM `Persons` WHERE sex='M'");
    
    // 获取单个值
    $db->select('ID')->from('Persons')->where('sex= :sex')->bindValues(array('sex'=>'M'))->single();
    //等价于
    $db->select('ID')->from('Persons')->where("sex= 'F' ")->single();
    //等价于
    $db->single("SELECT ID FROM `Persons` WHERE sex='M'");
    
    // 复杂查询
    $db->select('*')->from('table1')->innerJoin('table2','table1.uid = table2.uid')->where('age > :age')->groupBy(array('aid'))->having('foo="foo"')->orderByASC/*orderByDESC*/(array('did'))
    ->limit(10)->offset(20)->bindValues(array('age' => 13));
    // 等价于
    $db->query('SELECT * FROM `table1` INNER JOIN `table2` ON `table1`.`uid` = `table2`.`uid` WHERE age > 13 GROUP BY aid HAVING foo="foo" ORDER BY did LIMIT 10 OFFSET 20');
    
    // 插入
    $insert_id = $db->insert('Persons')->cols(array(
        'Firstname'=>'abc',
        'Lastname'=>'efg',
        'Sex'=>'M',
        'Age'=>13))->query();
    等价于
    $insert_id = $db->query("INSERT INTO `Persons` ( `Firstname`,`Lastname`,`Sex`,`Age`) VALUES ( 'abc', 'efg', 'M', 13)");
    
    // 更新
    $row_count = $db->update('Persons')->cols(array('sex'))->where('ID=1')->bindValue('sex', 'F')->query();
    // 等价于
    $row_count = $db->update('Persons')->cols(array('sex'=>'F'))->where('ID=1')->query();
    // 等价于
    $row_count = $db->query("UPDATE `Persons` SET `sex` = 'F' WHERE ID=1");
    
    // 删除
    $row_count = $db->delete('Persons')->where('ID=9')->query();
    // 等价于
    $row_count = $db->query("DELETE FROM `Persons` WHERE ID=9");
    
    // 事务
    $db->beginTrans();
    ....
    $db->commitTrans(); // or $db->rollBackTrans();