test=*# select * from armin ;
artikel | preis
---------+-------
1 | 10
2 | 5
(2 Zeilen)
test=*# select * from (select artikel, preis, avg(preis) over ()from armin) foo where avg < preis;
artikel | preis | avg
---------+-------+--------------------
1 | 10 | 7.5000000000000000
(1 Zeile)
test=*# select * from (select artikel, preis, avg(preis) over ()from armin) foo where avg > preis;
artikel | preis | avg
---------+-------+--------------------
2 | 5 | 7.5000000000000000
(1 Zeile)