I have 2 tables, A and B. I need all columns from A + 1 column from B in my select. Unfortunately, B has multiples rows(all identicals) for 1 row in A on the join condition.
I tried but I can't isolate one row in A for one row in B with left join for example while keeping my select.
How can I do this query ? Query in ORACLE SQL
Thanks in advance.
This is a good use for outer apply
. The structure of the query looks like this:
select a.*, b.col
from a outer apply
(select top 1 b.col
from b
where b.? = a.?
) b;
Normally, you would only use top 1
with order by
. In this case, it doesn't seem to make a difference which row you choose.
You can group by
on all columns from A
, and then use an aggregate (like max
or min
) to pick any of the identical B values:
select a.*
, b.min_col1
from TableA a
left join
(
select a_id
, min(col1) as min_col1
from TableB
group by
a_id
) b
on b.a_id = a.id
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