Col1 Col2
_________
A   |  1
A   |  2
A   |  3
B   |  4
B   |  5
B   |  6
and i need to obtain something like this
col1 list
________
A   | 1,2,3
B   | 4,5,6
i'm still beginner give me the most simple alternative
Col1 Col2
_________
A   |  1
A   |  2
A   |  3
B   |  4
B   |  5
B   |  6
and i need to obtain something like this
col1 list
________
A   | 1,2,3
B   | 4,5,6
i'm still beginner give me the most simple alternative
Try the following with array_agg
select
    col1,
    array_agg(col2)
from yourTable
group by
    col1
or with string_agg
select
    col1,
    string_agg(col2, ', ')
from yourTable
group by
    col1
