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Yes, your derived table can be any valid query.
Just to recap, the query structure from the previous answer looked
like this:
select d.foo
from (
select ...
from store_sales
where ...
) as d
A derived table is the result
of running the query that is inside the parentheses.
More correctly, it's a subquery, because it's inside the
main query. Notice that the outer query's SELECT clause
uses the "d." prefix on the columns.
You can put any query into parentheses in
the FROM clause like this. However, it is usually necessary
to name the derived table, and that's done with the AS clause,
which assigns a table alias. Some database systems
allow you to omit this alias:
select foo
from (
select ...
from store_sales
where ...
)
However, you would of course need to use
an alias if you wanted to join the derived table
to another table in the main query.
Your syntax error might be the result of using the
AS keyword in Oracle. For some reason, Oracle doesn't allow it.
Try this instead:
select d.foo
from (
complex 5-table query here
) d
Note the AS keyword is omitted.
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