Mysql NOT IN and NOT EXIST the same?

Question

I sometimes interchanged the use of NOT IN and NOT EXIST in my sql queries and both yield the same result. Is the logic behind the NOT EXIST

Answer 1

Both will give you the same results. The NOT EXISTS is a correlated sub-query, it is joined to the main query. In the example below, the NOT EXISTS should perform faster on a large dataset.

Find products without orders.

select *
  from Products
 where ProductId NOT IN (select ProductId FROM Orders)

select *
  from Products
 where NOT EXISTS (select 1 FROM Orders WHERE orders.ProductId = Products.Id)