Mysql Unique record 2 columns

Question

I am making an application which inserts users into a MySQL database.

I know you can make a column value unique, but I want a combination of 2 columns in a record to be unique.

For example:

id   firstname   lastname    creationdate

-----------------------------------------

 1   John        Doe         (today)

What I want to achieve is that I can enter a record like :

 2, John, Deo, (today)

but I cannot enter:

2, John, Doe, (today)

What SQL statement can I use to make a combination of multiple columns unique?

Answer 1

use the below query

ALTER TABLE Persons
ADD CONSTRAINT pk_PersonID PRIMARY KEY (FirstName,LastName)

http://www.w3schools.com/sql/sql_primarykey.asp

Mysql Unique record 2 columns

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