Question

I have an input for date. The format is YYYY-MM-DD. However, MM and DD are optional. All the following constitute for expected format:

• 2012-10-13
• 2012-09
• 2010

I need to store this data in MySQL database. It is going to be used for both: to display date and to filter (query) results.

What is the way to do it?

Answer 1

Simply set the month/day to 00 in a DATETIME column. For example:

2012-04-06
2012-04-00
2012-00-00

All of those examples are perfectly valid in DATETIME columns. As working proof, we (the company I work for) use this to specify book’s published dates for our website. We’re currently on MySQL 5.1.54.

Note: Depending on the language used to format dates (if any), you may need to format them differently depending on whether day/month is provided. For example, in PHP, I needed to check if the day was provided, and manually change the last ‘-00’ to ‘-01’, and then format the date appropriately (leaving out the day in the final result).

From the Manual (source)

Thanks to @jon for tracking this down:

MySQL permits you to store dates where the day or month and day are zero in a DATE or DATETIME column. This is extremely useful for applications that need to store birthdates for which you may not know the exact date. In this case, you simply store the date as ‘2009-00-00’ or ‘2009-01-00’. If you store dates such as these, you should not expect to get correct results for functions such as DATE_SUB() or DATE_ADD() that require complete dates. To disallow zero month or day parts in dates, enable the NO_ZERO_IN_DATE SQL mode.