mysql查询不适用于where子句和变量

Question

我试图使用mysql where子句从表中获取数据。但它不会返回任何值或错误。

这是函数

function getMsgByName($sender){
        global $connection;
        $sender  = mysqli_real_escape_string($connection,$sender);

        $query = "SELECT Message FROM chat WHERE Sender ='$sender'";
        $run = mysqli_query($connection,$query);
        $messages = array();
        while($message = mysqli_fetch_assoc($run)){
            $messages[] = array('message'=>$message['Message']);
        }
        return $messages;

    }