mysql si no existe

No soy un experto en bases de datos de ninguna manera, pero así es como lo hago.

http://www.somethinghitme. com/2010/05/06/mysql-almacenado-procedimientos-si-no-existe/

    DECLARE SomeId int;
    DECLARE CheckExists int;
    SET CheckExists = 0;  

    SELECT 1 INTO CheckExists from lookup_table WHERE someField = in_SomeParam LIMIT 1;   

    IF (CheckExists > 0) THEN
        SELECT id INTO SomeId FROM lookup_table WHERE someField = in_SomeParam;
    ELSE
        INSERT INTO lookup_table (someField ) VALUES(in_SomeParam);
        SELECT SomeId = LAST_INSERT_ID();
    END IF;