Question

I currently have 5 tables:

trialSum
-------------
id    total
-------------
1     2000
2     1000
3     500

trialLand
-------------
id    total
-------------
1     1000
2     250
3     500

trialImp
-------------
id    total
-------------
2     250

trialBldg
-------------
id    total
-------------
1     1000
2     500

trial
---------------------
id    name     info
---------------------
1     xxxxx    xxxxx
2     xxxxx    xxxxx
3     xxxxx    xxxxx
4     xxxxx    xxxxx

The trial table will have the most entries into and all of the “id” fields match up with each other. Each table will have over 7000 entries in them. I am trying to create one big table that looks like:

    trial
    ----------------------------------------------------------------------
    id    name     info    totalSum    totalLand    totalImp    totalBldg
    ----------------------------------------------------------------------
    1     xxxxx    xxxxx    2000        1000         0           1000
    2     xxxxx    xxxxx    1000        250          250         500
    3     xxxxx    xxxxx    500         500          0           0
    4     xxxxx    xxxxx    0           0            0           0

If I do a giant MySQL query that has 4 left joins, it take over 40 minutes to complete. There has to be an easier way. Thanks!

Answer 1

I would say that, the left join is indeed a good way to do this. Do you have indexes on those id columns? Try adding indexes and the speed should improve. Remember to use EXPLAIN to confirm the indexes are being used appropriately. More on EXPLAIN http://www.dbtuna.com/article.asp?id=14 .