PHP date input format - php

Question

Created a PHP input form to POST dates into SQL query, on the server side we have 0000-00-00 date format but locally we use the 00/00/0000 format, how do get the input form to accept the 00/00/0000 format to be used in the SQL query? By now we force the users to put the 0000-00-00 and it works perfectly but a lot of them are complaining about that!
<form action="index.php" method="POST">
<cust>From: </cust><input name="start_date" placeholder=" 0000-00-00" />
<cust>Until: </cust><input name="end_date" placeholder=" 0000-00-00" />
<select name="RegioSelect" placeholder="Choose"><option></option>
<?php
$region = $_POST["RegioSelect"];
$fdate = $_POST["start_date"];
$edate = $_POST["end_date"];
if(empty($fdate)){
$fdate = '2000-01-01';
} else {
$fdate;
}
if(empty($edate)){
$edate = date("Y/m/d");
} else {
$edate;
}
We were thinking convert on server side but in that case we can't use dates to compare date ranges. We convert them after retrieving to user's info as follows:
$new_fdate = strtotime($fdate);
$FiDate = date('d/m/Y',$new_fdate);
changed '$edate' to date("Y-m-d");
$new_edate = strtotime($edate);
$EnDate = date('d/m/Y',$new_edate);
?>
<input type="submit" value="Select region">
</select></br>
</form>
<?php
if(empty($region)){
$region = ' ';
} else {?><h4><?php echo $region; ?></h4><cust><b>From:</b><?php echo $FiDate; ?> <b>Until:</b> <?php echo $EnDate; ?></cust>
<?php
}
?>

Answer 1

Solved this as follows, now it works other side around, the input form accept 00/00/0000 date format but get converted to server side once POSTED.
<form action="list.php" method="POST">
<cust>From: </cust><input name="start_date" placeholder=" 00/00/0000" />
<cust>Until: </cust><input name="end_date" placeholder=" 00/00/0000" />
<select name="RegioSelect" placeholder="Choose"><option></option>
<?php
$region = $_POST["RegioSelect"];
//ORIGINAL VARIABLES
/*$fdate = $_POST["start_date"];
$edate = $_POST["end_date"];
*/
$fdate = date_format(date_create_from_format('d/m/Y', $_POST["start_date"]), 'Y-m-d');
$edate = date_format(date_create_from_format('d/m/Y', $_POST["end_date"]), 'Y-m-d');
if(empty($fdate)){
$fdate = '01/01/2000';
} else {
$fdate;
}
if(empty($edate)){
$edate = date("Y/m/d");
} else {
$edate;
}
So the code tells the query to choose all data between $fdate and $edate, if $fdate is empty take 01/01/2000 as first date and if $edate is empty take TODAY() as end date.