Adrian Klaver <adrian.klaver@xxxxxxxxxxx> writes: > On 7/25/19 12:23 PM, Kevin Brannen wrote: >> We're trying to understand what happened with a SELECT INTO. The problem >> can be see with this example: >> >> nms=# select into t2 from t1; >> SELECT 5 >> # select * from t2; >> -- >> (5 rows) > The list of output expressions after SELECT can be empty, producing a > zero-column result table. This is not valid syntax according to the SQL > standard. PostgreSQL allows it to be consistent with allowing > zero-column tables. However, an empty list is not allowed when DISTINCT > is used. Right, you selected no columns from t1, so t2 has no columns (and yet five rows). Worth noting here is that psql is a bit squirrely about displaying zero-column results --- it drops the column-names header line, and it doesn't emit a blank-line-per-row as one might expect. Perhaps somebody ought to fix that, but it's such a corner case that no one has bothered yet. regards, tom lane
