MySQL Conditional Insert

Question

I am having a difficult time forming a conditional INSERT

I have x_table with columns (instance, user, item) where instance ID is unique. I want to insert a new row

Answer 1

Have you ever tried something like that?

INSERT INTO x_table
SELECT 919191 as instance, 123 as user, 456 as item
FROM x_table
WHERE (user=123 and item=456)
HAVING COUNT(*) = 0;