Question

Suppose I have 2 fields: first_name and last_name.

It is ok to have first name duplicate, or last name duplicate, but, if both first_name and last_name are the same, do not insert! It’s like 2 unique keys, linked.

Answer 1

If the table already exists, then you can alter it to add a composite unique key:

ALTER `table_name` ADD UNIQUE (`first_name`,`last_name`);