Question

I’m having trouble writing this Query. I have 2 tables, vote_table and click_table. in the vote_table I have two fields, id and date. the format of the date is “12/30/11 : 14:28:36”. in the click_table i have two fields, id and date. the format of the date is “12.30.11”.

The id’s occur multiple times in both tables. What i want to do is produce a result that contains 3 fields: id, votes, clicks. the id column should have distinct id values, the votes column should have the total times that ID has the date 12/30/11% from the vote_table, and the clicks should have the total times that ID has the date 12.30.11 from the click table, so something like this:

ID | VOTES | CLICKS

001 | 24  |  50

002  |  30  |  45

Answer 1

Assuming that the types of the ‘date’ columns are actually either DATE or DATETIME (rather than, say, VARCHAR), then the required operation is fairly straight-forward:

SELECT v.id, v.votes, c.clicks
  FROM (SELECT id, COUNT(*) AS votes
          FROM vote_table AS v1
         WHERE DATE(v1.`date`) = TIMESTAMP('2011-12-30')
         GROUP BY v1.id) AS v
  JOIN (SELECT id, COUNT(*) AS clicks
          FROM click_table AS c1
         WHERE DATE(c1.`date`) = TIMESTAMP('2011-12-30')
         GROUP BY c1.id) AS c
    ON v.id = c.id
 ORDER BY v.id;

Note that this only shows ID values for which there is at least one vote and at least one click on the given day. If you need to see all the ID values which either voted or clicked or both, then you have to do more work.

If you have to normalize the dates because they are VARCHAR columns, the WHERE clauses become correspondingly more complex.