Hello
I have a table that has six columns. If the fourth column is null, then the first three columns, which are not nullable, must be unique, but if the fourth column is not null, then all the four columns must be unique.
Example of allowed cases:
COL1 COL2 COL3 COL4 COL5 COL6
1 1 1 NULL 123 125
1 1 2 NULL 123 125
1 2 1 NULL 123 125
2 1 1 NULL 123 125
1 1 1 1 123 125
Example of not allowed cases
COL1 COL2 COL3 COL4 COL5 COL6
1 1 1 1 123 125
1 1 1 1 123 125 INSERT/UPDATE MUST FAIL
1 2 1 NULL 123 125
1 2 1 NULL 123 125 INSERT/UPDATE MUST FAIL
There is a way to create a constraint that prevent any insertion in the table that do not accomplish these conditions?
Thanks