mysqli_real_escape_string（）在服务器中返回空字符串

Question

<?php
                $cser = mysqli_connect("localhost","root","","karmsys") or die("server connection failed:".mysql_error());
                if (isset($_POST["submit"])) {
                    $name = $_POST["name"];
                    $comment = mysqli_real_escape_string($_POST["comment"]);
                    $clientPic = mysqli_real_escape_string(date("Y-m-d-H-i-s")) . ".jpg";
                    $image_tmp = $_FILES['clientPic']['tmp_name'];
                    $confirm = "No";
                    echo "Name: " . $name . "<br>Comment: " . $comment . "<br>Pic: " . $clientPic ;
                    move_uploaded_file($image_tmp,"images/client/$clientPic");
                    $query="insert into review values (
                          null,'".$name."',
                          '".$comment."',
            '".$confirm."',
            '".$clientPic."'
                      )";
                    $result = $cser->query($query);
                    if($result > 0){
                        ?>
                            <div class="alert alert-success alert-dismissable">
                              <a href="#" class="close" data-dismiss="alert" aria-label="close">&times;</a>
                              <strong>Success!</strong> We got your comment. Wait till verify
                            </div>
                        <?php
                    } else {
                        ?>
                            <div class="alert alert-danger alert-dismissable">
                              <a href="#" class="close" data-dismiss="alert" aria-label="close">&times;</a>
                              <strong>AWW!</strong> Something gone wrong. Try Again
                            </div>
                        <?php
                    }
                }
        ?>

这是我的代码。我在谷歌搜索mysqli_real_escape_string在服务器上没有工作，并且只有一个结果在real_escape之前建立了连接，我做了但是它仍然在localhost上工作但不在服务器上