Hi Tom,
Thanks for your time.

We have the scenario like this...

DML on the table t should not populate the table with duplicate entries.

So if we have table with data in it as :

create table t ( x number);

insert into t values (1);

insert into t values (2);


commit;


then
I cannot insert the values 1 or 2 - because these already exists.
I cannot update these values 1 to 2 or 2 to 1 - this will create duplicate entries.


Actually , if we enable unique constraint then job is done.. but application is not allowing the same... i.e. due to unique constraint error .. application is stopping as execption is not handled.. it would take some time to change the code but immediate requirement is to avoid the duplicate entries in the table t.

so something like trigger deleting INSERTED row if the inserted data is violating the uniqueness or trigger updating the new updated values with the old values if new updated data is violating the uniqueness.

we used the trigger to achieve this it is resulting into table mutation.

I know the best way is to enforce the unique constraint, but that is not the need of the hour.

many thanks for your help.

regards