The MERGE statement is a very powerful way to combine INSERT, UPDATE and/or DELETE in a single statement. But there’s more than meets the eye. There are situations where you could use a MERGE statement to perform just one of those tasks.
The OUTPUT clause allows you to combine DML statements with a kind of SELECT statement on the rows affected by the DML operation. This is a powerful way to visualize what records were touched by your statement, or an easy way to build an auditing mechanism.
A trigger is like a stored procedure that automatically (and atomically) executes on a given condition, for instance when you insert a record into a table. Used properly, this is a powerful tool to enforce business rules, perform automated calculations, log changes, and more. But triggers also come with some potential pitfalls.