Oracle SQL invalid identifier error in nested WITH subquery - sql

Question

Below you will find three sample tables and data along with a query. This example might seem contrived, but it is part of much larger (nearly 1500 lines) SQL query. The original query works great, but I've run into a problem while adding some new functionality.
CREATE TABLE rule_table (
id_rule_table NUMBER (10),
name VARCHAR2 (24),
goal NUMBER (10),
amount NUMBER (10)
);
INSERT INTO rule_table (id_rule_table, name, goal, amount) VALUES(1, 'lorem', 2, 3);
INSERT INTO rule_table (id_rule_table, name, goal, amount) VALUES(2, 'ipsum', 3, 3);
INSERT INTO rule_table (id_rule_table, name, goal, amount) VALUES(3, 'dolor', 4, 3);
CREATE TABLE content_table (
id_content_table NUMBER (10),
name VARCHAR2 (24),
show_flag NUMBER (10)
);
INSERT INTO content_table (id_content_table, name, show_flag) VALUES(1, 'lorem', 0);
INSERT INTO content_table (id_content_table, name, show_flag) VALUES(2, 'ipsum', 1);
INSERT INTO content_table (id_content_table, name, show_flag) VALUES(3, 'dolor', 1);
CREATE TABLE module_table (
id_module_table NUMBER (10),
id_content_table NUMBER (10),
name VARCHAR2 (24),
amount NUMBER (10)
);
INSERT INTO module_table (id_module_table, id_content_table, name, amount) VALUES(1, 2, 'lorem', 10);
INSERT INTO module_table (id_module_table, id_content_table, name, amount) VALUES(2, 2, 'ipsum', 11);
INSERT INTO module_table (id_module_table, id_content_table, name, amount) VALUES(3, 2, 'dolor', 12);
SELECT RULE.id_rule_table
FROM rule_table RULE
WHERE (
CASE
WHEN RULE.goal <= (
WITH contentTbl (id_content_table)
AS (
SELECT id_content_table
FROM content_table
WHERE show_flag = 1
),
modulesTbl (id_content_table, id_module_table)
AS (
SELECT C.id_content_table, M.id_module_table
FROM contentTbl C
JOIN module_table M ON M.id_content_table = C.id_content_table
WHERE 4 < M.amount - RULE.amount
)
SELECT SUM(M.id_module_table)
FROM contentTbl C
JOIN modulesTbl M ON C.id_content_table = M.id_content_table
)
THEN 1
ELSE 0
END
) = 1;
DROP TABLE rule_table;
DROP TABLE content_table;
DROP TABLE module_table;
If you try this you will receive the error ORA-00904: "RULE"."AMOUNT": invalid identifier. The problem lies with the line "WHERE 4 < M.amount - RULE.amount".
If you replace RULE.amount, in that line, with some number (e.g., WHERE 4 < M.amount - 3) then the query will run just fine.
As mentioned above, this is a snippet test case from a much larger query, so the structure of the query can't be (or hopefully doesn't need to be) changed too much. That is, ideally I'm looking for a solution that will allow me to use RULE.amount in the sub-query without changing anything other that the SQL inside of the "WHEN RULE.goal <= ()" block.
I'm trying to run this on Oracle 11g.
One last thing, I tried searching google and stackoverflow for solutions, but I couldn't figure out the correct terminology to describe my issue. The closest thing seemed to be nested correlated subquery, but that doesn't seem to be exactly right.

Answer 1

Taking into account that this is only part of a much larger query, here are the surgical changes required to make this work:
Move the WHERE 4 < M.amount - RULE.amount condition out of the CTE and into the main query so that RULE is in scope.
Modify the modulesTbl CTE to return an additional column amount so that M.amount is now available to the main query.
With these 2 changes, the query would look like this:
SELECT RULE.id_rule_table
FROM rule_table RULE
WHERE (
CASE
WHEN RULE.goal <= (
WITH contentTbl (id_content_table)
AS (
SELECT id_content_table
FROM content_table
WHERE show_flag = 1
),
modulesTbl (id_content_table, id_module_table, amount) -- add amount
AS (
SELECT C.id_content_table, M.id_module_table, M.amount -- add amount
FROM contentTbl C
JOIN module_table M ON M.id_content_table = C.id_content_table
)
SELECT SUM(M.id_module_table)
FROM contentTbl C
JOIN modulesTbl M ON C.id_content_table = M.id_content_table
AND 4 < M.amount - RULE.amount -- moved from CTE to here
)
THEN 1
ELSE 0
END
) = 1;