php - 如果存在则删除该记录，否则插入

Question

我有一个点击最喜欢的星星，我想检查数据库中是否有该记录，如果存在则删除该记录，如果不存在则插入该记录，记录未插入是什么问题

     <?php
    include "config.php";
    header('Content-Type: application/json');
    $landmarkid = $_GET['landmarkid'];
    $userid = $_GET['userid'];


    try {
        $query = mysqli_query($con,"SELECT * from favourite WHERE userid =$userid AND L_ID = $landmarkid");



        if(mysqli_num_rows($query) > 0)
        {
            $q1 = mysqli_query($con,"DELETE from favourite WHERE userid =$userid AND L_ID = $landmarkid");

            if($q1){
                echo '{"Deleted":"true"}';
            }
            else {
                echo '{"Deleted":"false"}';
            }
       } 
       else {
            $q2 = mysqli_query($con,"INSERT INTO favourite (userid,L_ID) VALUES ( $userid, $landmarkid) ");

            if($q2){
                echo '{"inserted":"true"}';
            }
            else {
                echo '{"inserted":"false"}';
            }
        }

        } catch (Exception $e) {
        echo 'Caught exception: ',  $e->getMessage(), "\n";
    }
?>

Answer 1

尝试在插入语句中添加单引号，看看是否有效。更改此声明；

$q2 = mysqli_query($con,"INSERT INTO favourite (userid,L_ID) VALUES ( $userid, $landmarkid) ");

对此；

$q2 = mysqli_query($con,"INSERT INTO favourite (userid,L_ID) VALUES ( '$userid', '$landmarkid') ");

如果有帮助或者您发现问题，请告诉我。