[Php]mysqli Operation Flow

<?PHPclasssqltools{Private $con; Private $trans;  Public function__construct ($host,$user,$pswd,$db){        $this->con =NewMysqli ($host,$user,$pswd,$db); if($this->con->connect_error) die("CONNECT ERROR:".)$this->con->connect_errno. ":".$this->con->connect_error. " <br/> "); $this->con->query ("Set Names UTF8"); }    /*Start Transaction*/     Public functionStart_trans () {$this->con->autocommit (false); $this->trans =true; }    /*rollback*/     Public functionrollback () {$this->con->rollback (); }    /*Add, insert, update and so on*/     Public functionExecute$sql){        $exec _bool=$this->con->query ($sql); if($exec _bool)             die("EXEC ERROR:".)$this->con->errno. ":".$this->con->error. " <br/> "); return $this->con->affected_rows; }    /*Select*/     Public function&execute_query ($sql){        $res=$this->con->query ($sql); if(!$res)             die("QUERY ERROR:".)$this->con->errno. ":".$this->con->error. " <br/> "); return $res; }    /*Free Resource*/     Public functionClose () {if($this-Trans)$this-rollback (); if($this-con)$this->con->Close (); }}

[Php]mysqli Operation Flow