Adrian Klaver <adrian.kla...@aklaver.com> 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
