Question

I have a table with 4 columns, id, Stream which is text, Duration (int), and Timestamp (datetime). There is a row inserted for every time someone plays a specific audio stream on my website. Stream is the name, and Duration is the time in seconds that they are listening. I am currently using the following query to figure up total listen hours for each week in a year:

SELECT YEARWEEK(`Timestamp`), (SUM(`Duration`)/60/60) FROM logs_main
WHERE `Stream`="asdf" GROUP BY YEARWEEK(`Timestamp`);

This does what I expect… presenting a total of listen time for each week in the year that there is data.

However, I would like to build a query where I have a result row for weeks that there may not be any data. For example, if the 26th week of 2006 has no rows that fall within that week, then I would like the SUM result to be 0.

Is it possible to do this? Maybe via a JOIN over a date range somehow?

Answer 1

The tried an true old school solution is to set up another table with a bunch of date ranges that you can outer join with for the grouping (as in the other table would have all of the weeks in it with a begin / end date).

In this case, you could just get by with a table full of the values from YEARWEEK:

201100
201101
201102
201103
201104

And here is a sketch of a sql statement:

SELECT year_weeks.yearweek , (SUM(`Duration`)/60/60) 

FROM year_weeks LEFT OUTER JOIN logs_main
   ON year_weeks.yearweek = logs_main.YEARWEEK(`Timestamp`)

WHERE `Stream`="asdf" GROUP BY year_weeks.yearweek;