Re: Puzzled by ROW constructor behaviour?

You've drawn a false equivalence from the similarity of the syntax.

The following also works:

SELECT 1 = (SELECT 1*1);

But I don't think there is any argument that while this works:

INSERT INTO tbl (col) SELECT 1*1;

This doesn't:

INSERT INTO tbl (col) 1;

There is no difference with replacing 1 with a composite type and the SELECT subquery with VALUES instead.

Your "VALUES" is just a scalar subquery expression that, if it indeed produces a single row and column, can be compared to any other scalar value (if it produces more than one row you will get an error - try it).

David J.