Update same table after Insert trigger

Question

I am working on a product in which I have to send SMS to concerned person when someone waits for more than 15 minutes for being served.

For that I have written a procedu

Answer 1

You cannot update the same table in Row-Level AFTER Trigger.
Change your Row-Level AFTER INSERT trigger to row-level BFEORE INSERT trigger.

But you UPDATE stmt inside the trigger will not effect the new record being inserted.

Wonder how it can be done, this is tricky.