What happens if you try to insert a duplicate value in a column with a unique constraint using an INSERT query?

When you try to insert a duplicate value in a column with a unique constraint using an INSERT query, the database management system (DBMS) will prevent the operation and throw an error. This is because the unique constraint ensures that all values in a column are different. Here's a step-by-step breakdown of what happens:

1. You execute an INSERT query to add a new row of data into a table. The data includes a value for a column that has a unique constraint.

2. The DBMS checks the existing values in the column to ensure that the new value does not already exist.

3. If the value already exists (i.e., it's a duplicate), the DBMS stops the INSERT operation.

4. The DBMS then throws an error indicating that you've tried to insert a duplicate value into a column with a unique constraint.

5. The new row of data is not added to the table.

This behavior is important for maintaining the integrity of the data in the database. It ensures that each value in a column with a unique constraint is indeed unique, which can be critical for columns like user IDs, email addresses, and other identifiers.