php-pdo存储json数据到Mysql中的unicode 反斜杠消失

//$value=array('test'=>'中文字符串',"中文字符串",121312,'test',mt_rand(1,9999));
//$value=json_encode($value);
//var_dump($value);
//$sql = "update user_1 set `val` = :val where `key` = 'u1001001' limit 1";
如果此处val=$value下面代码不变则入库后反斜杠被去掉。这算是个手误。:val要和下面的execute对应
//$dbname='dev_cssg_s1_user';
//$host='192.16.12.131';
//$dsn='mysql:host='.$host.'; port=3306; dbname='.$dbname;
//// 统一utf8编码
//$optArr=array(PDO::MYSQL_ATTR_INIT_COMMAND => 'SET NAMES UTF8');
//$pdoObj=new PDO($dsn, 'root', 'root', $optArr);
//$sth=$pdoObj->prepare($sql);
//$ret = $sth->execute(array(':val'=>$value));
//var_dump($ret);