MySQL: looking to SUM these UNIONs together

OK, my head hurts...!

This beautiful MySQL query:

(SELECT mtwitterfollowers AS twitfollow FROM `media` WHERE media.id=1)
UNION
(SELECT SUM(twitterfollowers) AS twitfollow FROM people LEFT JOIN peoplejoin ON peoplejoin.people_id = people.id LEFT JOIN positions ON position_id = positions.id WHERE peoplejoin.media_id = 1)
UNION 
(SELECT SUM(twitterfollowers) AS twitfollow FROM people LEFT JOIN peoplejoin ON peoplejoin.people_id = people.id LEFT JOIN networkjoin ON networkjoin.network_id = peoplejoin.network_id LEFT JOIN positions ON position_id = positions.id WHERE networkjoin.media_id = 1)

...returns three rows of pretty numbers.

Idea开发者_运维知识库lly, I'd like this query to return all three "twitfollow" results, SUMmed together.

However, putting a SUM round them gives me an error about "every derived table must have its own alias", and I'm a little confused as to quite how to do solve that.

(Of course, I could just sum the results in PHP; but I am assuming that it's quicker to do this using the MySQL server. Would I be right?)

Use your entire query as the FROM clause of another query:

SELECT SUM(twitfollow) FROM (
    (SELECT mtwitterfollowers AS twitfollow FROM `media` WHERE media.id=1)
    UNION ALL
    (SELECT SUM(twitterfollowers) AS twitfollow FROM people LEFT JOIN peoplejoin ON peoplejoin.people_id = people.id LEFT JOIN positions ON position_id = positions.id WHERE peoplejoin.media_id = 1)
    UNION ALL
    (SELECT SUM(twitterfollowers) AS twitfollow FROM people LEFT JOIN peoplejoin ON peoplejoin.people_id = people.id LEFT JOIN networkjoin ON networkjoin.network_id = peoplejoin.network_id LEFT JOIN positions ON position_id = positions.id WHERE networkjoin.media_id = 1)
) t1

I also changed your UNION to UNION ALL as you probably don't want to remove rows just because the sum from one table is equal to the sum from another table.

Why not making it shorter, like below?

SELECT SUM(
    (SELECT mtwitterfollowers AS twitfollow FROM `media` WHERE media.id=1)
    +
    (SELECT SUM(twitterfollowers) AS twitfollow FROM people LEFT JOIN peoplejoin ON peoplejoin.people_id = people.id LEFT JOIN positions ON position_id = positions.id WHERE peoplejoin.media_id = 1)
    +
    (SELECT SUM(twitterfollowers) AS twitfollow FROM people LEFT JOIN peoplejoin ON peoplejoin.people_id = people.id LEFT JOIN networkjoin ON networkjoin.network_id = peoplejoin.network_id LEFT JOIN positions ON position_id = positions.id WHERE networkjoin.media_id = 1)
) AS twitterfollowers

Just wrap a aggregating query around it:

SELECT SUM(twitfollow)
FROM
(
    (SELECT mtwitterfollowers AS twitfollow FROM `media` WHERE media.id=1)
    UNION ALL
    (SELECT SUM(twitterfollowers) AS twitfollow FROM people LEFT JOIN peoplejoin ON peoplejoin.people_id = people.id LEFT JOIN positions ON position_id = positions.id WHERE peoplejoin.media_id = 1)
    UNION ALL
    (SELECT SUM(twitterfollowers) AS twitfollow FROM people LEFT JOIN peoplejoin ON peoplejoin.people_id = people.id LEFT JOIN networkjoin ON networkjoin.network_id = peoplejoin.network_id LEFT JOIN positions ON position_id = positions.id WHERE networkjoin.media_id = 1)
)