On Sat, Jan 6, 2018 at 9:10 PM, Adrian Klaver <adrian.kla...@aklaver.com> wrote:
> On 01/06/2018 08:46 PM, Ken Tanzer wrote: > >> 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
