How Do I Use Case Statement Column In Group By

Question

As stated by the question, I\'m trying to formulate a query that has a case statement in the column results, and then I want to include that column in the query\'s group by stat

Answer 1

The alias isn't available to use in the GROUP BY because when GROUP BY happens the alias isn't defined yet:

Here's the order:
1.FROM
2.WHERE
3.GROUP BY
4.HAVING
5.SELECT
6.ORDER BY

You can work around that with:

SELECT column1,column2,case_column
FROM (
SELECT SOME_TABLE_ALIAS.COLUMN1, OTHER_TABLE_ALIAS.COLUMN2,
CASE
    WHEN SOME_TABLE_ALIAS.COLUMN3 IS NOT NULL THEN 'A'
    ELSE 'B'
END AS CASE_COLUMN
FROM SOME_TABLE SOME_TABLE_ALIAS
... (other table joins and where clauses)
) a
GROUP BY COLUMN1, COLUMN2, CASE_COLUMN

Or just use the case you use in SELECT in GROUP BY