SQL Insert into table only if record doesn’t exist [duplicate]

This might be a simple solution to achieve this:

INSERT INTO funds (ID, date, price)
SELECT 23, DATE('2013-02-12'), 22.5
  FROM dual
 WHERE NOT EXISTS (SELECT 1 
                     FROM funds 
                    WHERE ID = 23
                      AND date = DATE('2013-02-12'));

p.s. alternatively (if ID a primary key):

 INSERT INTO funds (ID, date, price)
    VALUES (23, DATE('2013-02-12'), 22.5)
        ON DUPLICATE KEY UPDATE ID = 23; -- or whatever you need

see this Fiddle.