pdo事物回滚

//需要修改表引擎为innodb,myisam不支持事物  
//alter table table_name engine=innodb;  
  
<?php  
public function index()  
{  
        $this->db->trans_begin();  
        $this->db->query("update pdotest set name='songzhongji' where id='11'");  
        $row = $this->db->affected_rows();  
        echo $row;  
        //影响行数为0 ==》回滚  
        if($row == 0 )  
        {  
            $this->db->trans_rollback();  
        } else {  
            //不为0 ，修改成功，进行添加  
            //判断状态，添加成功，进行提交  
            $this->db->query("insert into pdotest(name,pwd) VALUES ('123','456')");  
            if ($this->db->trans_status() === FALSE)  
            {  
                $this->db->trans_rollback();  
            }  
            else  
            {  
                $this->db->trans_commit();  
            }  
        }  
}