Question

I have an Oracle query, which has something to the effect of

Having Count(field) > (Long SQL statement that returns one row)
Both sides of the query work alone, but together I get a “not a group by” expression.

When replacing the long SQL statement with a number it works, but I assumed the two were equivalent if only one row is returned?

Edit
After doing some playing around I realized:
… Table T … Having Count(field) > (Long SQL statement with Table A Where A.field = T.field)
It works when I replace T.field with any of the specific options for T.field, but when I reference T.field specifically I get the same “not a group by expression”

Answer 1

SELECT ... 
FROM Table T ...
GROUP BY T.afield
HAVING Count(T.anotherfield) 
       > (Long SQL statement with Table A Where A.somefield = T.afield)

should work ok.

---

SELECT ... 
FROM Table T ...
GROUP BY T.anotherfield
HAVING Count(T.anotherfield) 
       > (Long SQL statement with Table A WHERE A.somefield = T.afield)

should not work. A field (like T.afield) that is not included in the GROUP BY list, cannot be referenced in SELECT, HAVING or ORDER BY clauses. Only aggregate functions of that field can be referenced – you could have WHERE A.somefield = MIN(T.afield) for example.