CODEWITHSUNDEEP
postgresqljoin
genesi5
genesi5

Reputation: 453

Join data from two tables via another table, postgresql

So, i'm fighting with that, can't find the solution. Here's problem: We have three tables. The first one is connected to second by id, the third is connected to second as well by id, and there's no connection between first an third.

enter image description here

I need to join name from first and sum of id from third table. i tried to use subqueries, but failed to organize joining.

Any suggestions?

Upvotes: 0

Views: 159

Answers (2)

James Shisiah
James Shisiah

Reputation: 383

In a three table join query, you could something like this:

    SELECT tab1.name, COUNT(tab3.id) AS sum_ids 
    FROM tab1 INNER JOIN tab2 ON tab1.id=tab2.tab1_id 
    INNER JOIN tab3 ON tab2.id=tab3.tab2_id GROUP BY tab1.id;

Upvotes: 1

Lajos Arpad
Lajos Arpad

Reputation: 76424

So you have a three-level category problem. This might help you

select Tab1.name, sum(Tab3.id)
from Tab1
join Tab2
on Tab1.id = Tab2.tab1_id
join Tab3
on Tab2.id = Tab3.tab2_id
group by Tab1.id

Upvotes: 1

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