获取所选下拉列表的值以与另一个下拉列表进行比较

Question

我有 2 个下拉列表，分支下拉列表从数据库中获取 app_cn。并且 sem 下拉列表获取 app_plan_no。但我需要将分支下拉列表中选择的值与 sem 下拉列表中选择的值进行比较。

我看到了这段代码，但我不知道该怎么做

   <?php
    $mysqli = new mysqli("localhost", "root", "", "app");
    $result = $mysqli->query("SELECT * FROM app GROUP BY app_cn ORDER BY app_cn");
    echo'<select name="drop_1" id="drop_1">';
     while($row = $result->fetch_assoc())
        {
           echo '<option value="'.$row['app_cn'].'">'.$row['app_cn'].'</option>';
        }
echo'</select>';

if($_GET['func'] == "drop_1" && isset($_GET['func'])) {
   drop_1($_GET['drop_var']); 
}

function drop_1($drop_var)
{
    $mysqli = new mysqli("localhost", "root", "", "app");
    $results = $mysqli->query("SELECT * FROM app WHERE app_cn='$drop_var' GROUP BY app_plan_no ORDER BY app_plan_no");

    echo '<select name="tier_two" id="tier_two">
          <option value=" " disabled="disabled" selected="selected">Choose one</option>';

          while($drop_2 = $results->fetch_assoc())
            {
            if($drop_2['app_plan_no'] != '')
            {
              echo '<option value="'.$drop_2['app_plan_no'].'">'.$drop_2['app_plan_no'].'</option>';
            }
            }

}
echo'</select>';
?>

<script type="text/javascript">
$(document).ready(function() {
    $('#wait_1').hide();
    $('#drop_1').change(function(){
            if( $(this).val() == "ALL") {
            $("#wait_1").hide();
            $("#result_1").hide();
        }else{
      $('#wait_1').show();
      $('#result_1').hide();
      $.get("func.php", {
        func: "drop_1",
        drop_var: $('#drop_1').val()
      }, function(response){
        $('#result_1').fadeOut();
        setTimeout("finishAjax('result_1', '"+escape(response)+"')", 400);
      });
      }
        return false;
    });
});

function finishAjax(id, response) {
  $('#wait_1').hide();
  $('#'+id).html(unescape(response));
  $('#'+id).fadeIn();
}
</script>

这就是我想做的WHERE app_cn='$drop_var'

我的桌子

counter | app_cn   | app_plan_no 

000004  |  comp1   |  1
000172  |  comp1   |  1
000007  |  comp1   |  2
000005  |  comp2   |  1

这是我的选择下拉菜单

<select name="branch" id="branch" onchange="showCourses()">
<option value="ALL" selected='ALL'>ALL</option>
<?php
$mysqli = new mysqli("localhost", "root", "", "app");
    $result = $mysqli->query("SELECT * FROM app GROUP BY app_cn ORDER BY app_cn");
     while($row = $result->fetch_assoc())
        {
           echo '<option value="'.$row['app_cn'].'">'.$row['app_cn'].'</option>';
        }?>
</select>
<select name="sem" id="sem" onchange="showCourses()">
<?php

$mysqli = new mysqli("localhost", "root", "", "app");
    $result = $mysqli->query("SELECT * FROM app GROUP BY app_plan_no ORDER BY app_plan_no");
     while($row = $result->fetch_assoc())
        {
           echo '<option value="'.$row['app_plan_no'].'">'.$row['app_plan_no'].'</option>';
        }
        ?>
</select>

Answer 1

要使用 jquery 获取 select 语句的值，请使用 .val()

要在使用 php（服务器端）提交表单时获取 select 语句的值，您可以在 $_POST 变量中找到变量的值，其中键是 select 语句的 name 属性的值。