HAVING without GROUP BY

Question

1. Is the following possible according to standard(!) SQL?
2. What minimal changes should be neccessary in order to be conforming to the standard (if it wasn\'t alr

Answer 1

From the standard (bold added from emphasis)

1) Let HC be the having clause. Let TE be the table expression that immediately contains HC. If TE does not immediately contain a group by clause, then “GROUP BY ()” is implicit. Let T be the descriptor of the table defined by the GBC immediately contained in TE and let R be the result of GBC.

With the implicit group by clause, the outer reference can access the TE columns.

However, the certification to these standards is very much a self-certification these days, and the example you gave would not work across all of the main RDBMS providers.