Select2 - 将多选写入数据库，双记录

Question

这里有一个有趣的问题。

我使用 Select2 允许用户用多个值填充选择框，然后将这些值写入数据库表中。但是，在将值插入表时，我注意到选择字段的最后一个值总是被写入两次。我怀疑foreach 循环有问题，但不知道如何解决。

选择字段是模式的一部分，在单击“保存”按钮后，它会通过 AJAX 发送到我的 ajax.php 文件，在该文件中处理插入。同样的方法在整个网站上多次部署都没有问题，只有在 multiple 字段时才会出现问题。

HTML

<!-- Department -->
<label>Department Name:</label>
<div class="input-group">
    <span class="input-group-addon"><i class="fa fa-bars"></i></span>
    <input type="text" class="form-control" id="addDeptName" name="addDeptName" />
</div>
<!-- /.Department -->

<p> </p>

<!-- Positions -->
<label>Department Positions:</label>
<div class="input-group">
    <span class="input-group-addon"><i class="fa fa-briefcase"></i></span>
    <select class="form-control select2" style="width:100%;" id="addDeptPositions" name="addDeptPositions" multiple>
        <option value="Option1">Option1</option>
        <option value="Option2">Option2</option>
        <option value="Option3">Option3</option>
        <option value="Option4">Option4</option>
    </select>
</div>
<!-- /.positions -->

JS

// ADD NEW RECORD TO DATABASE           
$("#NewDepartmentButton").click(function() {
    $("#addDeptName").focus();

    // check that input fields are not empty
    if($("#addDeptName").val()!="" && $("#addDeptPositions").val()!="") {

        $.ajax({
            url: "../../plugins/MySQL/ajax_action.php",
            type: "POST",
            //async: true, 
            data: { action:"new_department",Department_Name:$("#addDeptName").val(),Department_Positions:$("#addDeptPositions").val()}, // form data to post goes here as a json object
            dataType: "html",           

            success: function(data) {
                $('#department_output').html(data); 
                drawVisualization();
            },  
        });
    } else {
        //notify the user they need to enter data
        alert("Please enter a valid Department Name.");
        return;
    }

    // close modal and refresh page
    $('#NewDepartmentModal').modal('hide');
    setTimeout(function(){location.reload()}, 2000);

    // Reload Datatables
    //$('#department_table').DataTable().ajax.reload();

    // refresh entire website
    //location.reload();

    return;
});

PHP

if(isset($_POST['action']) && ($_POST['action']=='new_department')) {

    // include connection details
    include 'connect_db.php';

    //Open a new connection to the MySQL server
    $db = new mysqli($dbhost,$dbuser,$dbpass,$dbname);

    //Output any connection error
    if ($db->connect_error) {
        die('Error : ('. $db->connect_errno .') '. $db->connect_error);
    }

    // get variables and sanitize
    $addDeptName = mysqli_real_escape_string($db,$_POST['Department_Name']);
    $addDeptPositions = $_POST['Department_Positions'];

    // create new record
    foreach ($addDeptPositions as $c) {
        $sql = "INSERT INTO `qci_departments` (`Department`,`Positions`) VALUES ('".$addDeptName."', '".mysqli_real_escape_string($db, $c)."')";
        $db->query($sql);
    }

    if (!$db->query($sql)) {
        echo "
            <div class=\"alert alert-danger alert-dismissible\">
                <button type=\"button\" class=\"close\" data-dismiss=\"alert\" aria-hidden=\"true\">&times;</button>
                <h4><i class=\"icon fa fa-ban\"></i> Error!</h4>
                There was an error while excuting this query.<br />
                (" . $db->errno . ") " . $db->error . "
              </div>";
    }

    echo "
        <div class=\"alert alert-success alert-dismissible\">
            <button type=\"button\" class=\"close\" data-dismiss=\"alert\" aria-hidden=\"true\">&times;</button>
            <h4><i class=\"icon fa fa-check\"></i> Alert!</h4>
            Success, record updated successfully. Refreshing database now...
        </div>";

    //close connection
    $db->close();

}

数据库结果： 例如。如果从多个字段中选择职位“客户经理”和“应收账款主任”：

编辑： 问题似乎与数组提交有关，因为这是选择值的样子：

Array ( [0] => Accounting Manager [1] => Accounts Receivable Officer ) Array ( [0] => Accounting Manager [1] => Accounts Receivable Officer )

编辑 2： 在 JS 代码中添加了return;

Answer 1

问题似乎出在 AJAX 交互上，更具体地说是mysqli_real_escape() 和 SQL 语句。

我将foreach 循环更改为此，它奇迹般地工作了，尽管更改仅包括重命名 SQL 变量和删除转义字符串（我后来再次添加并且仍然有效）。

// create new record
foreach ($addDeptPositions as $c) {
    $sql2 = "INSERT INTO `qci_departments` (`Department`,`Positions`) VALUES ('".$addDeptName."', '".mysqli_real_escape_string($db,$c)."')";
    $db->query($sql2);
}

不知道为什么会这样，但现在可以了 :)