How can I "SELECT out" multiple differently-defined rows from a large join table without re-defining it for each row

I am using postgres.

What I have right now is like this:

SELECT <statement> FROM (
<MASSIVE JOIN STATEMENT>
)
UNION ALL
SELECT <different statement> FROM (
<SAME MASSIVE JOIN STATEMENT>
)

What I would really like is to have is a way to accomplish the same thing without having to put in the same massive join statement multiple times. Is there a way to accomplish this?

Thank You!!

I tried giving the table an alias and referencing the alias in the second SELECT statement, but it didn’t work. Postgres says the relation does not exist.

>Solution :

Given its the same source for both selects, have you tried using a CTE?

e.g:

WITH CTE AS (
  -- Your MASSIVE JOIN STATEMENT here
)

SELECT <statement> FROM CTE
UNION ALL
SELECT <different statement> FROM CTE;