mysql> select oseba.priimek, sum(kosov) from trgovec, oseba, kupcija where trgovec.oid=oseba.oid and trgovec.tid=kupcija.tid group by oseba.priimek;
+---------+------------+
| priimek | sum(kosov) |
+---------+------------+
| Adamic | 5000 |
| Bajec | 700 |
| Cokan | 600 |
| Jazbec | 3200 |
| Smolar | 900 |
| Trcek | 200 |
+---------+------------+
6 rows in set (0.00 sec)
mysql> select oseba.priimek, sum(kosov) from trgovec, oseba, kupcija where trgovec.oid=oseba.oid and trgovec.tid=kupcija.tid group by oseba.priimek and sum(kosov) < 2000;
ERROR 1111 (HY000): Invalid use of group function
mysql>