WHY???

you can use the following

[font="Courier New"]SELECT

x,

y,

COUNT(y) AS How_Many_Times

FROM t1

GROUP BY x, y

HAVING (COUNT(y) > 1)[/font]

I don't understand 1.why do you have to add a rowid!! 2.what is the purpose of adding a third column (z) with a default value of zero!!!