Notes on grouping behavior

Setting an alias to be the same as a selected attribute can change the attribute source. For example, in the following query, amount in stmt1_amount refers to stmt1.amount, while amount in stmt2_amount refers to stmt2.amount:

SELECT stmt1 AS SELECT amount AS amount;
SELECT stmt2 AS SELECT amount+1 AS stmt1_amount, amount+2 AS amount, amount+3 AS stmt2_amount FROM stmt1

This also applies when using the GROUPING and GROUPING_ID functions:

SELECT stmt1 AS SELECT amount AS amount;
SELECT GROUPING(amount) AS stmt1_amount, amount AS amount,
  GROUPING(amount) AS stmt2_amount, orders AS orders,
  FROM stmt1 
  GROUP BY CUBE(amount, orders)

Implicit selects can be added to the end of the select list. For example, the following two queries are equivalent:

SELECT COUNT(sales) AS cnt GROUP BY totals, price

SELECT COUNT(sales) AS cnt, totals AS totals, price AS price GROUP BY totals, price