SQL - Relationship between a SubQuery and an Outer Table

Question

Problem

I need to better understand the rules about when I can reference an outer table in a subquery and when (and why) that is an inappropriate re

Answer 1

How about the following query:

SELECT t1.* FROM 
(
  SELECT * 
  FROM 
  (
    SELECT t2.id,
    RANK() OVER (PARTITION BY t2.id, t2.date ORDER BY t2.date DESC) AS R  
    FROM table2 t2
  )
  WHERE R = 1
) sub 
INNER JOIN table1 t1 
ON t1.id = sub.id