What are triggers in database?

Question

triggers

Answer 1

http://www.mysqltutorial.org/sql-triggers.aspx
Refer this for practical examples

Answer 2

On some modification (insert , delete ,update) in database an event should trigger or happen . To achieve this feature there are trigger in database.
Example : suppose you have a warehouse that stores products , and if the number of products falls below certain minimum value , then an event should trigger that alerts the user to add some more products or you can automatically place order of more products