Subquery nesting

Question

How many sub queries can be nested within one another?

Answer 1

Potentially, as many as you want. But it would probably get down the performance of your query.

Answer 2

Technically as many as you want but realistically after two or three it gets really confusing and can hinder performance of the machine you are running it on.

Answer 3

Agreed with other replies but Oracle Database imposes no limit on the number of subquery levels in the FROM clause of the top-level query. You can nest up to 255 levels of subqueries in the WHERE clause.