So, most databases have a 'default' date format that is set by whoever installs your database. For example, our current default date format for an Oracle database I work with has a DD-MON-YY default format. In general, you should always use some variant of an explicit TO_DATE($string_date,$format) converting function so that you don't get any surprises (like when you submit 05/04/06 and end up with April 6, 2005 instead of May 4, 2006).