php - 如何确保在检查时该值仅保存到表中一次？

Question

使用我的代码，如果用户选中其中一个名称旁边的复选框 当用户单击“保存”时，名称将保存到我的 review_shared 表中。

但我只想保存选中的值 一旦进入表格，它就会按照现在的方式保存多次 - 我的意思是，如果用户返回此页面并检查名称，然后用户再次单击“保存”。

我可以在代码中添加什么来实现这一点，这样它只会在我的 review_shared 表中保存一次？目前它看起来像这样，它保存了多次:

if(!empty($_POST['check_contacts'])) {
    foreach($_POST['check_contacts'] as $check) {

        //$_GET['id'] is the current review for which contacts are being edited, we are checking a contact to share that review with
            $insert_review_shared_command = "INSERT INTO review_shared VALUES(NULL," .$_GET['id']. ", '$user_id','$check')";

        //we want to save the checked contacts into the review_shared table
        $insert_into_review_shared_table = mysqli_query($con,$insert_review_shared_command);

    }

        //go to the main page when changes have been saved
    header('Location:volleyLogin.php');
}

    $con->close();

我认为在上面添加这样的代码会有帮助，但事实并非如此:

        if(!empty($_POST['check_contacts'])) {

    //************************* added this in **************
                $check="";
        //if the contact in review_shared is already checked, we don't want to save it multiple times
            $already_checked = "SELECT * from review_shared WHERE user_id = '$user_id' AND contact_id = '$check' AND review_id = " .$_GET['id'];

            $already_checked_result=mysqli_query($con,$already_checked);
            $num_rows = mysqli_num_rows($already_checked_result);

            if($num_rows >= 1) {
            echo "This is already a contact";
            break;
            }

//*******************************************************

        foreach($_POST['check_contacts'] as $check) {

            //$_GET['id'] is the current review for which contacts are being edited, we are checking a contact to share that review with
                $insert_review_shared_command = "INSERT INTO review_shared VALUES(NULL," .$_GET['id']. ", '$user_id','$check')";

            //we want to save the checked contacts into the review_shared table
            $insert_into_review_shared_table = mysqli_query($con,$insert_review_shared_command);

        }

            //go to the main page when changes have been saved
        header('Location:volleyLogin.php');
    }

        $con->close();

Answer 1

break; 用于退出循环(for、foreach、while 和 do-while)和 switch 结构，而不是来自 if block 。您必须创建一个与 that if block 相对应的 else block ，并将整个 foreach 循环放在那里。

// your code
if($num_rows) {
    echo "This is already a contact";
}else{
    foreach($_POST['check_contacts'] as $check) {

        //$_GET['id'] is the current review for which contacts are being edited, we are checking a contact to share that review with
        $insert_review_shared_command = "INSERT INTO review_shared VALUES(NULL," .$_GET['id']. ", '$user_id','$check')";

        //we want to save the checked contacts into the review_shared table
        $insert_into_review_shared_table = mysqli_query($con,$insert_review_shared_command);

    }
}
// your code

相关引用资料如下:

• http://php.net/manual/en/control-structures.break.php