ORACLE DATABASE INTERVIEW QUESTIONS

What is a UNIQUE constraint in Oracle?

How do you define a UNIQUE constraint when creating a table?

What happens if you try to insert a duplicate value into a column with a UNIQUE constraint?

How can you add a UNIQUE constraint to an existing table?

Can a table have multiple UNIQUE constraints? If so, how does it work?

What is the difference between a UNIQUE constraint and a PRIMARY KEY constraint?

How can you create a composite UNIQUE constraint on multiple columns?

How do you disable and enable a UNIQUE constraint?

What is the impact of a UNIQUE constraint on database performance?

Explain how to use a UNIQUE constraint in combination with a FOREIGN KEY constraint?