Question

I got table with 3 columns (Primary)id, type, name. I am inserting data into this table, and I need to prevent multiple rows with the same type and name. How can I check this and insert in one query?

I was trying

IF ((select id from models where type = 1 and name = 'test') is null)
THEN insert into models(type, name) values(1, 'test');
END IF;

but it is not working and I have no idea why( 0 experience with conditions in mysql) – it is giving me syntax error

#1064 - You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'IF ((select id from models where type = 1 and name = 'test') is null)
THEN inse' at line 1 

Answer 1

If this is needed in general (not only for this Insert), you should add a UNIQUE constraint on the (type, name) combination:

ALTER TABLE models
  ADD UNIQUE KEY type_name_U (type, name) ;

Then you can simply add rows and if the combination exists in the table, the Insert will fail:

INSERT INTO  models(type, name)
  VALUES (1, 'test') ;

---

For one-time check only, try this instead:

INSERT INTO  models(type, name)
  SELECT 1, 'test'
  FROM dual
  WHERE NOT EXISTS
        ( SELECT *
          FROM models
          WHERE type = 1 
            AND name = 'test'
        )