Question

I have a chat user entry in a MySql table –

id (primary key, autoincrement) – the chat user id
user_id – the users id as it pertains to our product
room_id – the id of the room your in

If a chat operator enters the room, leaves, and then comes back – as it is now – will create two entries in the room (INSERT INTO chatuser …)

I know INSERT IF NOT EXISTS syntax, however I want to IF NOT EXISTS not on the primary key, but WHERE user_id = x AND room_id = y (which will be the same if they re-enter a room they have been in)

something like INSERT INTO chatuser SET user_id=4, room_id=2 IF ENTRY DOESNT EXIST WITH THOSE VALUES ALREADY 😉

thank you

Answer 1

If you have a unique index on (user_id,room_id), you can do INSERT ... ON DUPLICATE KEY UPDATE (or INSERT IGNORE if you don’t need to update anything when the record already exists):

INSERT INTO table_1 (user_id, room_id, enter_date)
VALUES  (1,1, NOW())
ON DUPLICATE KEY UPDATE
enter_date = NOW()

// or
INSERT IGNORE INTO table_1 (user_id, room_id)
VALUES (1,1)