php – 何时调用mysqli :: close

我何时应该调用 mysqli :: close？我从来没有习惯使用if语句来检查bind_param(),prep()和execute()是否成功.我应该在方法的末尾(下面)调用$stmt-> close().或者我应该在每个条件之后调用它,确保我关闭数据库连接,即使进程在某个阶段失败,例如bind param.

public function function_name($id,$new_id ){
    $query = "UPDATE TABLE SET name = ? WHERE field = ? ";
    if($stmt=$this->prepare($query)){
        if($stmt->bind_param("is",$id,$new_id)){
            if($stmt->execute()){

            }else{//Could not execute the prepared statement
                $message = "Could not execute the prepared statement";
            }
        }else{//Could not bind the parameters
            $message = "Could not bind the parameters";
        }
    }else{
        $message = "Could not prepare the statement";
    }
    return $message
}

mysqli_kill();
mysqli_close();