Impossible to store certain datetime formats in SQL Server

Question

At the moment I have a column that holds timestamps as a datetime

The data is being stored as 10/30/2011 10:50:34 AM

My goal is to

Answer 1

SQL Server doesn't store a DateTime in any string format - it's stored as an 8 byte numerical value.

The various settings (language, date format) only influence how the DateTime is shown to you in SQL Server Management Studio - or how it is parsed when you attempt to convert a string to a DateTime.

There are many formats supported by SQL Server - see the MSDN Books Online on CAST and CONVERT. Most of those formats are dependent on what settings you have - therefore, these settings might work some times - and sometimes not.

The way to solve this is to use the ISO-8601 date format that is supported by SQL Server - this format works always - regardless of your SQL Server language and dateformat settings.

The ISO-8601 format is supported by SQL Server comes in two flavors:

• YYYYMMDD for just dates (no time portion) - note here: no dashes!, that's very important! YYYY-MM-DD is NOT independent of the dateformat settings in your SQL Server and will NOT work in all situations!

or:

• YYYY-MM-DDTHH:MM:SS for dates and times - note here: this format has dashes.

This is valid for SQL Server 2000 and newer.

If you use SQL Server 2008 and the DATE datatype (only DATE - not DATETIME!), then you can indeed also use the YYYY-MM-DD format and that will work, too, with any settings in your SQL Server.

Don't ask me why this whole topic is so tricky and somewhat confusing - that's just the way it is. But with the YYYYMMDD format, you should be fine for any version of SQL Server and for any language and dateformat setting in your SQL Server.