根据PHP中选择的第一个下拉列表填充第二个下拉列表

Question

I am using PHP and Postgresql/PostGIS data base. My database schema is something like this.

1. divname | distname
2. dhaka | Manikganj
3. dhaka | Narayanganj
4. dhaka | Munshiganj
5. Khulna | Jessore
6. Khulna | Kushtia
7. Khulna | Meherpur

I am using the following codes

<?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);
?>

Currently its populating all the divname and distname in the dropdown but I want if the "Dhaka" is selected only the distname under the dhaka will show in the second dropdown.

Thanks

Answer 1

There should be where clause in

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

Edit like this,

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