Difference between EXISTS and IN in SQL?

Question

What is the difference between the EXISTS and IN clause in SQL?

When should we use EXISTS, and when should we use IN

Answer 1

Difference lies here:

select * 
from abcTable
where exists (select null)

Above query will return all the records while below one would return empty.

select *
from abcTable
where abcTable_ID in (select null)

Give it a try and observe the output.