Setting Field to NULL in MYSQL

I am having problems updating a specific field to NULL in MYSQL.

$sql = "update tbluser 
         set mode ='".$mode."',
         paydate = curdate(),
         [COLOR="red"]cancel_date = '',[/COLOR]
         where username ='".$_SESSION['UserLogged']."'";

mysql_query($sql) or die("Not Updated..");

Code (markup):

In the structure of the table, cancel_date is defined as a DATE, the NULL is set to YES, and the default is NULL.

I have tried:
cancel_date = NULL
cancel_date = ' '
and tried not updating it since it defaults to NULL.

But for some reason when the update is executed, the field is being updated to " 1999-11-30".

Any clues? Thanks

 

Hi, try

$sql = "update tbluser 
         set mode ='".$mode."',
         paydate = curdate(),
         cancel_date=DEFAULT(cancel_date)
         where username ='".$_SESSION['UserLogged']."'";

mysql_query($sql) or die("Not Updated..");

PHP:

Regards

 

Just do
cancel_date=NULL

 

Thanks! I will try that, koko5.