Where Exists vs Join

4 Answers. EXISTS is only used to test if a subquery returns results, and short circuits as soon as it does. JOIN is used to extend a result set by combining it with additional fields from another table to which there is a relation.

When to use exists vs join?

4 Answers. EXISTS is only used to test if a subquery returns results, and short circuits as soon as it does. JOIN is used to extend a result set by combining it with additional fields from another table to which there is a relation.

Where exist vs inner join?

3 Answers. Generally speaking, INNER JOIN and EXISTS are different things. The former returns duplicates and columns from both tables, the latter returns one record and, being a predicate, returns records from only one table. If you do an inner join on a UNIQUE column, they exhibit same performance.