How to give a unique constraint to a combination of columns in Oracle?

Question

I have a Table with 4 Columns

Each Column will be A,B,C,D

Column A is the Primary key. Column B has unique name constraint.

Now I want to remove the

Answer 1

Create a unique key on those columns

ALTER TABLE YourTable
  add CONSTRAINT YourTable_unique UNIQUE (B, C, D);

Oracle/PLSQL: Unique Constraints