apologize if there is the same question.
When I started my career, my manager told me that you don't need to use "WITH", you can do anything with "JOIN".
Now I am wondering is it any performance differences between them. Why do I need to use WITH clause?
Update: I am not sure it is the exact comparation that we can use both and check any performance differences but here is an example:
WITH query_name1 AS ( SELECT ... FROM table_1 ) , query_name2 AS ( SELECT ... FROM table_2 ... ) SELECT ...
Select ... FROM ( SELECT ... FROM table_1 LEFT JOIN table_2 )