根据第一个选择获取选项值

Question

我想根据第一个选项类型中的选择角色在第二个选项中获取用户。我有多个用户表。我想要根据角色选择第一个选项值的记录，然后记录将根据选择从表中提取。我在这里只插入了1个表代码。我希望当用户选择npa时，reocrd将从npa表中获取。/*Ajax.php*/include('config.php');if(!empty($_POST["role"])){    // Fetch state data based on the specific country    $query = "SELECT * FROM promotor";    $result = mysqli_query($conn , $query);    // Generate HTML of state options list    if(mysqli_num_rows($result) > 0){        echo '<option value="">Select User</option>';        while($row = mysqli_fetch_assoc($result)){            echo '<option value="'.$row['Promotor_ID'].'">'.$row['Promotor_Name'].'</option>';        }    }else{        echo '<option value="" class="form-control">User not available</option>';    }<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>    <script type="text/javascript">    //alert(role);    $(document).ready(function(){        $('#role').on('change', function(){            var role = $(this).val();            if(role){                alert(console.log(role));            }                $.ajax({                    type:'POST',                    url:'ajax.php',                    data:'role='+role,                    success:function(html){                        $('#user').html(html);                    }                });            }        else{                $('#user').html('<option value="">User Not Available</option>');            }        });</script> <select id="role" name="role" class="form-control"> <option value="default">Select Role</option> <option value="NPA">NPA</option> <option value="BDA">BDA</option> </select>  <select id="user" name="user" class="form-control"> <option value="">Select User</option> </select>

Answer 1

<?php

<?php

/*getcustomer.php*/

include('config.php');

$sql = "select * from promotor";

$result = mysqli_query($conn, $sql);

?>

<select id="user">

    <option value="">Select Country</option>

    <?php

    if(mysqli_num_rows($result)){

        while($row = mysqli_fetch_assoc($result)){

            echo '<option value="'.$row['Promotor_ID'].'">'.$row['Promotor_Name'].'</option>';

        }

    }else{

        echo '<option value="">User Not Available</option>';

    }

    ?>

</select>

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>

<script>

    function showCustomer(str) {

        var xhttp;

        if (str == "") {

            document.getElementById("txtHint").innerHTML = "";

            return;

        }

        xhttp = new XMLHttpRequest();

        xhttp.onreadystatechange = function() {

            if (this.readyState == 4 && this.status == 200) {

                document.getElementById("txtHint").innerHTML = this.responseText;

            }

        };

        xhttp.open("GET", "getcustomer.php?q="+str, true);

        xhttp.send();

    }

</script>

<select id="role" name="role" class="form-control" onchange="showCustomer(this.value)">

 <option value="default">Select Role</option>

  <option value="NPA">NPA</option>

  <option value="BDA">BDA</option>

 </select>

<div id="txtHint">User list will be here</div>