Tutorial to get values from database on selection of dropdown in PHP

PHP Fetch Tutorial

Fetching Data From Database on selection of dropdown value

Step 1: 

Get the list of countries from database and populate in drop-down.

[php]
$ctry_qry = mysql_query(“SELECT * FROM countries ORDER BY name;”);?>
//Calling Function
<select name="”ctry”"> <option value="”&quot;">Select Country</option></select>
<select name="”ctry”"><option value="”<?PHP">”><!–?PHP echo $ctry[‘name’]; ?–></option></select>
[/php]

Consider that we choose  India from the dropdown list.

countries-dropdown-list-values-from-database

Step:2

          Add a simple javascript function which will run onchange

[javascript]
function reloaddata(ctryid) {
window.location.href="http://localhost/rotatetheglobe/admin/try.php?ctryid=" + ctryid;
}
[/javascript]

Step:3

        Reload the page in JS and pass the currently selected country id

values-fetched-from-db-on-country-selection

Step:4

Get the country id from query string and fetch the required values from the database

[php]
<?PHP</pre>
<div><code>if</code><code>(isset(</code><code>$_REQUEST</code><code>[</code><code>’ctryid'</code><code>])) {</code></div>
<div><code>$ctryinfo_qry</code> <code>= mysql_query(</code><code>"SELECT * FROM country_info where ctry_root_id=’"</code><code>.</code><code>$_REQUEST</code><code>[‘ctryid</code><code>’]."'</code> <code>ORDER BY ctry_info_id ;");</code></div>
<div><code>?></code></div>
<pre>[/php]

Fetch array is used to fetch the respective row from record set . Using fetch array in while loop is used get a new row of MySQL information until the condition is TRUE.When there are no more rows the function will return FALSE causing the while loop to stop!

[php]
<textarea id="msgpost" name="ctry_about" rows="10" cols="50"> <?php echo $ctry_inf[‘ctry_about’];?></textarea>
<!–?php } ?–>

[/php]

CLICK HERE to view the complete output

Possible Errors to occur:

  • JS Error
  • Couldn’t get the value from the query string
  • Page not found

Must Follow

  • Make Sure the querystring variable and the $_REQUEST variable is same
  • Make sure your onchange function is same name as that you call in your code.

Must know before reading this article

  • PHP Basics
  • HTML Basics
  • DB Handling

Coming Up:

  • How to configure a site to work in your local host when you are running windows

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