Hello, I am new to SQL. I am currently using PostGres, but i think querying is pretty much the same?

I have the following tables:
common, cds, and position

cds inherits common

common and cds are linked by 'id'.

common has values start and stop.

I want to find all the 'position.target_pos' that lie within a cds region (the start and stop are obtained from common).


I have this query:

however, this is returning me the value of over 1,000 which is impossible if my query is correct because there are only 800 entried in the position table. Therefor, i'm pretty sure my query is wrong, but i'm not sure where!!

Please help!

Play around with smaller tables and you'll learn how joins work.

If you have two tables, one with 4 rows and one with 5 rows, the join will return 4 * 5 = 20 rows if you have no join condition.

(BTW, maybe you need some more join condition on the positions table.)