Question

I’m trying to wrap my head around how to get a distinct count of days a user logged in, when the db has each login session stored with a time and date stamp (DATETIME column). EG:

USERID | TIME | BOUGHT  
--------------------------
4 | 2012-07-16 04:44:52   | 3
4 | 2012-07-16 04:45:52   | 2  
5 | 2012-07-16 04:54:52   | 5
4 | 2012-07-18 04:44:52   | 3
4 | 2012-07-18 04:45:52   | 2  
4 | 2012-07-21 04:54:52   | 5

I want to search for how many times user 4 bought from the site – and the query should return 3 (because user 4 visited the site a total of 3 days). Do I have to use a PHP/MYSQL combination or can I do it in SQL?

Answer 1

SELECT USERID, COUNT(DISTINCT DATE(TIME)) FROM my_table GROUP BY USERID

See it on sqlfiddle.