Hi. You can have multiple columns with the same name, and use it as a subselect, like this silly example:
SELECT 'a' AS my_col,'b' AS my_col,'foo' AS other; SELECT * FROM (SELECT 'a' AS my_col,'b' AS my_col,'foo' AS other) foo;
But is there any way to select either of those columns without taking all the fields with *?
SELECT my_col,other FROM (select 'a' AS my_col,'b' AS my_col,'foo' AS other) foo; ERROR: column reference "my_col" is ambiguous
I suspect there isn't, but just wondering if there's some way I'm not aware of.
?: SELECT bar.my_col, foo.my_col FROM (SELECT 'a' AS my_col) as bar , (select 'b' AS my_col,'foo' AS other) foo;
my_col | my_col --------+-------- a | b
Though I would think this would just be pushing the point where you get confused what my_col is really pointing to down the road.
Thanks Adrian, but I was really wondering about the case where the two columns are already in a single result set. I came across this issue accidentally, and it's not causing any problems. Just trying to understand the possibilities/limitations for future reference.
Cheers,
Ken
So having thought about this a little more, it seems like once you create a result set with identically-named columns, those columns are effectively crippled. In that they can be viewed (via SELECT *), but not referenced, used or acted upon in any way. Still just wanting to confirm this is/is not the case. Thanks!
