call function from multiple options - php

Question

I am using PHP to call the database to print 3 different dropdown menus. That works. My problem is calling the function and passing the dropdown selections into the function and displaying the records after the submit button is pressed. The function is a build query taking into account if only 1 of the dropwdowns are selected or all 3.
The function is currently in the same page as the the form.
Here is the form:
<form action="edit.php" method="POST">
<select>
<?php $getGroup = mysql_query("SELECT DISTINCT resgroup FROM restable ORDER BY resgroup");
while($viewAllGroups = mysql_fetch_array($getGroup)){
?>
<option id="<?php echo $viewAllGroups['resgroup']; ?>"><?php echo $viewAllGroups['resgroup']; ?></option><?php } ?>
</select>
<select>
<?php $getType = mysql_query("SELECT DISTINCT restype FROM restable ORDER BY restype");
while($viewAllTypes = mysql_fetch_array($getType)){
?>
<option id="<?php echo $viewAllTypes['restype']; ?>"><?php echo $viewAllTypes['restype']; ?></option><?php } ?>
</select>
<select>
<?php $getService = mysql_query("SELECT DISTINCT service FROM restable ORDER BY service");
while($viewAllServices = mysql_fetch_array($getService)){
?>
<option id="<?php echo $viewAllServices['service']; ?>"><?php echo $viewAllServices['service']; ?></option><?php } ?>
</select>
<input type="submit" class="btn btn-primary" value="Filter" />
</form>
Here is the function:
<?php
function displayrecords(){
$groups = $_POST['resgroup'];
$type = $_POST['restype'];
$service = $_POST['service'];
if($groups != ""){
$where[] = " `resgroup` = '".mysql_real_escape_string($group)."'";
}
if($type != ""){
$where[] = " `restype` = '".mysql_real_escape_string($type)."'";
}
if($service != ""){
$where[] = " `service` = '".mysql_real_escape_string($service)."'";
}
$sql_json = "SELECT * FROM mytable WHERE $where_clause ORDER BY id DESC";
}
?>
Then I try to display the function.
<?php displayrecords(); ?>
I am not getting an error, however, once the submit button clicked, the dropdown menu's clear out, and it doesn't return anything. I know I'm missing a lot. I would appreciate any help.
Thank you in advance.

Answer 1

First of all please provide name to each select element. Again in the the edit.php file access the values of post array by that name.
Now I am giving an example for it.
HTML part:
<select name='select1' >
<option value='1'>Value</option>
<option value='1'>Value</option>
</select>
Now in edit.php you can access the value of selected element of selectbox select1
as $_POST['select1'];

Answer 2

You are adding an Array into the string, which will only result in "SELECT * FROM mytable WHERE Array() ORDER BY id DESC"; or something similar.
Try to add this befor your $sql_json = "...line:
$where = implode(" AND ", $where);
This should add restype=value AND service=value etc to your string.
Additionally, you are referencing to $group instead of $groups in your if($groups != "") clause.
Also, you have to give your select tags a name to be able to reference them in $_POST:
<select name="restype">

Answer 3

You need to alter your PHP because the sql statement is looking for a variable $where_clause and I don't see it defined in your code.
You can rewrite the building of the where clause
<?php
function displayrecords(){
$groups = $_POST['resgroup'];
$type = $_POST['restype'];
$service = $_POST['service'];
$where = "";
if($groups != ""){
$where = " `resgroup` = '".mysql_real_escape_string($group)."'";
}
if($type != ""){
if( $where != "" ) $where .= " AND ";
$where .= " `restype` = '".mysql_real_escape_string($type)."'";
}
if($service != ""){
if( $where != "" ) $where .= " AND ";
$where .= " `service` = '".mysql_real_escape_string($service)."'";
}
$sql_json = "SELECT * FROM mytable WHERE $where ORDER BY id DESC";
}
?>