Create constraint in alter table without checking existing data

Question

I\'m trying to create a constraint on the OE.PRODUCT_INFORMATION table which is delivered with Oracle 11g R2. The constraint should make the PRODUCT

Answer 1

You can certainly create a constraint which will validate any newly inserted or updated records, but which will not be validated against old existing data, using the NOVALIDATE keyword, e.g.:

ALTER TABLE PRODUCT_INFORMATION
  ADD CONSTRAINT PRINF_NAME_UNIQUE UNIQUE (PRODUCT_NAME)
  NOVALIDATE;

If there is no index on the column, this command will create a non-unique index on the column.