Left Join and Sum()
I though this was basic but some help are needed..
I do a left join because there MIGHT exist records in table2.
select table1.amount, table2.prize
from table1
left join table2 on table1.id = table2.table1id
My problem begins here,
select sum(table1.amount - table2.prize) as houseWin
from table1
left join table2 on table1.id = table2.table1id
Sum is removing all records that does not corresponds in table2.
Sum() goes totally wrong when grouping records.
WANT THIS
IF amount and prize exist the result is, do (amount-prize)
IF there aren't a prize (returns null in left join) the result is (amount-0)
Help!
I do a left join because there MIGHT exist records in table2.
select table1.amount, table2.prize
from table1
left join table2 on table1.id = table2.table1id
My problem begins here,
select sum(table1.amount - table2.prize) as houseWin
from table1
left join table2 on table1.id = table2.table1id
Sum is removing all records that does not corresponds in table2.
Sum() goes totally wrong when grouping records.
WANT THIS
IF amount and prize exist the result is, do (amount-prize)
IF there aren't a prize (returns null in left join) the result is (amount-0)
Help!
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dingir,Glad to help :)What I meant was that in your original query, you have some instances where there is a number for table1.amount, but table2.prize was null. Any time you try to perform an operation where at least one side is null, the result will be null.COALESCE worked because it substituted a non-null value, in this case zero, any time table2.prize was null.Patrick
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