mercredi 4 février 2015

Count values from one table using two columns in another table


I have a problem. I have table_1 (col1, col2, value) and table_2 (col1, col2).


I want to count values from table_1 but only the rows which exist in table_2. In both tables col1 and col2 are key (not primary).


I've tried:



select col1, col2, sum(value)
from table_1
where table_1.col2 in (select col2 from table_2)
group by col1, col2 ;


It works , but wrong, select too many rows from table_1





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