What are some examples of primary keys in SQL?

What are some examples of primary keys in SQL?

Primary keys are unique identifiers for records in a table. Examples include 'id' in a users table or 'order_number' in an orders table.

Can a primary key be a combination of multiple columns?

Yes, a primary key can be a composite key, which is made up of two or more columns to uniquely identify a record.

What happens if I try to insert a duplicate primary key?

Inserting a duplicate primary key will result in an error, as primary keys must be unique for each record.

Are primary keys the same as unique keys?

Not exactly. While both enforce uniqueness, a primary key cannot accept null values, whereas a unique key can.