*** WRONG ANSWER *** (or at least not a very efficient or simple answer)
SELECT * FROM yourtable WHERE DATE(yourtimestampfield) = '2013-1-13'
Or, if you want to match to *today*, it is even simpler:
SELECT * FROM yourtable WHERE DATE(yourtimestampfield) = CURDATE()
The DATE( )
function in MySQL extracts the data alone from a date and time field.
So, for example, it converts '2013-1-22 17:13:12' to just '2013-1-22' for you.