php date and timestamp subtraction

So I need to query a mysql database and get a timestamp and a date out of it. I have to subtract the timestamp from the date with php to find the number of days between the 2. Query is easy, but how do I subtract the 2?

Timestamp: 2009-12-23 11:49:56
Date: 2010-01-06

Just doing $data['date']-$data['timestamp'] obviously doesn't work. So how do I have to mod them to do it?

 

Figured it out. I used strtotime to convert the strings from the query to time in seconds. Then subtracted the 2. Then divided it by 86400 (number of seconds in a day). Then type cast it to int to truncate it and just get the number of full days between the 2 dates.