根據PHP中選擇的第一個下拉列表填充第二個下拉列表

Question

我正在使用PHP和Postgresql / PostGIS數據庫。 我的數據庫架構是這樣的。

1. divname | 地名
2. dhaka | 曼尼甘傑
3. dhaka | 納拉揚甘傑
4. dhaka | 芒希甘傑
5. 庫爾納| 傑索爾
6. 庫爾納| 庫什蒂亞
7. 庫爾納| 梅赫布爾

我正在使用以下代碼

<?php
$con = pg_connect("Connection Parameter");
if (!$con)
  {
  die("Could not connect: " . pg_last_error());
  }
$divquery = "SELECT DISTINCT divname FROM union_bgd 
        ORDER  BY divname";
$distquery = "SELECT DISTINCT distname FROM union_bgd
        ORDER  BY distname";
$resultDiv = pg_query($con, $divquery); 
$resultDist = pg_query($con, $distquery);

    ?>
    Division
  <select id="division" name="division" onclick = "">
  <option value="" selected="selected">Select a Division</option>
  <?php
      while($dd1 = pg_fetch_array( $resultDiv )) 
        {

        echo '<option value= "' . $dd1['divname'] . '">' . $dd1['divname'] . '</option>';

        }

    ?>

</select></br>
District
<select id="district" name="district" onclick = "">
  <option value="" selected="selected">Select a District</option>
  <?php
      while($dd2 = pg_fetch_array( $resultDist )) 
        {

        echo '<option value= "' . $dd2['distname'] . '">' . $dd2['distname'] . '</option>';

        }

    ?>

</select>

 <?php   
pg_close($con);
?>

當前，它在下拉列表中填充所有divname和distname，但我想如果選擇“ Dhaka”，則僅在dhaka下的distname將顯示在第二個下拉列表中。

謝謝

Answer 1

應該有where子句

$distquery = "SELECT DISTINCT distname FROM union_bgd ORDER  BY distname";

像這樣編輯

$distquery = "SELECT DISTINCT distname FROM union_bgd where divname=".$selected_dist." ORDER  BY distname";