Hi

I have Table with Two columns

1)SID
2)Owner

First Time No check on insertion:

user has entered record:
SID owner
1 avi


Next time User inserts with same SID must have owner as avi.
means:

SID owner
1 avi is right entry( This entry can be multiple)

1 Julian is wrong entry


is there any check or constraint in oracle for these types of checks

pls. Suggest
rgds.

Avi kumar