Why doesn't SUM work????

[NotionCommotion]

Anyone know why the following doesn't work? I believe I may have to "group" them, but am not sure on the process. Thank you!

SELECT SUM(t1.c1) AS t1c1_sum, t2.c1 AS t2c1 FROM t1, t2;

[chazzy]

how are these 2 tables related? you can't just group things of data that aren't related.

[NotionCommotion]

I should have added that each table has another column called user_id. t1 might have multiple rows with a given user_id, but t2 will have only 1 row per user_id. The query should only return results when the user_id is equal to 1 (or whatever).

Thanks

[chazzy]

since you're still being vague, the only thing i can say is that the group by clause looks like this:

GROUP BY column_name;

where column name is typically whatever you have in your sum.

[NotionCommotion]

Wasn't trying to be elusive. The "whatever" was meant to imply that the id might change. This seems to work. The GROUP was actually on the non-summed column and I expect this was to ensure that only one row is returned. This is still very foriegn to me, and I am sure you will see more beginner questions from me. Thank you for your help.

SELECT SUM(t1.c1) AS t1c1_sum, t2.c1 AS t2c1
FROM t1
JOIN t2 ON t1.user_id=t2.user_id
WHERE t2.user_id=1
GROUP BY t2.c1;