Using MD5 and CONCAT in MuSQL WHERE clause - mysql

Question

I am creating a reset password procedure. this way:
1- Send reset email to the user (whom forgot his/her password), and this email contain a link to this address:
http://www.example.com/resetpassword.php?userid=1b2798bad6ee465d967cdb71ced504f7
The value of the parameter [userid] is generated by this PHP code:
<?php
md5($row_Recordset2['userID'].date('d-m-Y'));
?>
Note: I did this so that I can get a unique parameter value containing: The MD5 hash of the real user id + the current date (concatenation) , Why? so the link in the email will be available for the current date only. I do not want that link to work in the next day.
2- When the person click on the above link, he/she will be taken to the page [resetpassword.php]
3- In the page [resetpassword.php] page I have this piece of code:
$colname_Recordset1 = "-1";
if (isset($_GET['userid'])) {
$colname_Recordset1 = $_GET['userid'];
}
mysql_select_db($database_aaa_database, $aaa_database);
$query_Recordset1 = sprintf("SELECT * FROM users WHERE md5(CONCAT(userID,
DATE_FORMAT(NOW(),'%d-%m-%Y'))) = %s ", GetSQLValueString($colname_Recordset1,
"text"));
$Recordset1 = mysql_query($query_Recordset1, $aaa_database) or die(mysql_error());
$row_Recordset1 = mysql_fetch_assoc($Recordset1);
$totalRows_Recordset1 = mysql_num_rows($Recordset1);
The SELECT statement return [Query was empty] ... What is the problem and how to solve it?
I have tested this MySQL statement manually:
SELECT userFirstName, md5(CONCAT(userID, DATE_FORMAT(NOW(),'%d-%m-%Y'))) from users
And it return many rows, one of the rows is like this:
Sam 1b2798bad6ee465d967cdb71ced504f7
So, the:
md5(CONCAT(userID, DATE_FORMAT(NOW(),'%d-%m-%Y')))
works fine and it return the same exact value generated by the PHP code :
<?php
md5($row_Recordset2['userID'].date('d-m-Y'));
?>
PHP give: 1b2798bad6ee465d967cdb71ced504f7
MySQL give: 1b2798bad6ee465d967cdb71ced504f7
But this:
md5(CONCAT(userID, DATE_FORMAT(NOW(),'%d-%m-%Y')))
seems to be NOT WORKING in the WHERE clause:
sprintf("SELECT * FROM users WHERE md5(CONCAT(userID,
DATE_FORMAT(NOW(),'%d-%m-%Y'))) = %s ", GetSQLValueString($colname_Recordset1,
"text"));
By the way, I am using Dreamweaver.
I don't know how to solve this problem. Any help will be highly appreciated.