mysql – INSERT Query with WHERE condition

Question:

How can I make an insert with a where condition?

I have the following query:

INSERT INTO `registro`(`id`, `username`)

values

('','USER_1'),
('','USER_2'),
('','USER_3')

It will add a new user in the record table. But I need him to check if this user already exists in the DB, if it already exists he shouldn't insert it. This check should only be done for the username column.

I read in some places that the INSERT does not accept the WHERE, in which case how should it be done?

Answer:

In SQL, you can do it like this

  INSERT INTO pessoa (id, nome, sexo, datanascimento, cpf) 
       SELECT 227,'FULANDO DE TAL','F','1999-09-09', '999.999.999-9'
WHERE NOT EXISTS (SELECT 1 FROM pessoa WHERE id = 227);