Oracle passing outer query value to inner query - sql

Question

This might be a simple but I need to apply the logic in other:
WITH t(col) AS (
SELECT 1 FROM dual
UNION SELECT 2 FROM dual
UNION SELECT 3 FROM dual
UNION SELECT 4 FROM dual
UNION SELECT 5 FROM dual
)
SELECT col , --- will works as usual
(SELECT col FROM t WHERE col = outer_q.col) new_col, --working as well
(
SELECT sum (latest_col)
from
(
SELECT col latest_col FROM t WHERE col = outer_q.col
UNION ALL
SELECT col FROM t WHERE col = outer_q.col
)
)newest_col -- need to get an output "4"
from t outer_q where col = 2;
An simple output like:
COL NEW_COL NEWEST_COL
---------- ---------- ----------
2 2 4
I just need to use the outer most value to the inner I used for the third column
EDITING-- sample with more data:
WITH
t(col) AS
( SELECT 1 FROM dual
UNION
SELECT 2 FROM dual
UNION
SELECT 3 FROM dual
UNION
SELECT 4 FROM dual
UNION
SELECT 5 FROM dual
),
t1(amount, col) AS
(SELECT 100 , 2 FROM dual
UNION
SELECT 200, 3 FROM dual
)
SELECT col,
(SELECT col FROM t WHERE col = outer_q.col
) new_col,
(SELECT SUM(x)
FROM
(SELECT col x FROM t
UNION ALL
SELECT amount x FROM t1
)
WHERE col = outer_q.col
) newest_col -- gives 315 as it takes whole `SUM`
FROM t outer_q
WHERE col = 2;
An output is expected like:
COL NEW_COL NEWEST_COL
---------- ---------- ----------
2 2 102
Thanks in advance for any help.

Answer 1

Well, you can if you refactor a but your query:
WITH t(col) AS (
SELECT 1 FROM dual
UNION SELECT 2 FROM dual
UNION SELECT 3 FROM dual
UNION SELECT 4 FROM dual
UNION SELECT 5 FROM dual
)
SELECT col,
(SELECT col FROM t WHERE col = outer_q.col) new_col,
(SELECT sum (latest_col)
from
(
SELECT col latest_col FROM t
UNION ALL
SELECT col FROM t
) x
where x.latest_col = outer_q.col
) newest_col -- need to get an output "4"
from t outer_q where col = 2;
This is possible here because outer_q is now in the where clause of the sub-query. It was used before in the sub-sub-query (the one with the UNION ALL), and this one was hiding it.
To try to make things clearer, now we have something like:
with t as (...)
select col,
(SELECT col FROM t WHERE col = outer_q.col) new_col,
(SELECT col FROM (Something more complex) WHERE ... = outer_q.col) new_col,
from t outer_q where col = 2;
So we now have the same level of "interiority".
EDIT: to answer the updated question, there is a little adaptation needed:
WITH t(col) AS
(
SELECT 1 FROM dual
UNION
SELECT 2 FROM dual
UNION
SELECT 3 FROM dual
UNION
SELECT 4 FROM dual
UNION
SELECT 5 FROM dual
),
t1(amount, col) AS
(
SELECT 100, 2 FROM dual
UNION
SELECT 200, 3 FROM dual
)
SELECT col,
(SELECT col FROM t WHERE col = outer_q.col) new_col,
(SELECT SUM(amount)
FROM
(SELECT col, col amount FROM t -- row is (1, 1), then (2, 2) etc
UNION ALL
SELECT col, amount FROM t1 -- row is (2, 100), then (3, 200) etc
)
WHERE col = outer_q.col
) newest_col -- gives 102 as it takes whole `SUM`
FROM t outer_q
WHERE col = 2;
The part to understand is in the innermost query: you want to sum both the column and the amount value, so you repeat the col value as if it was an amount.
Another way to obtain the same result (with more performance, I guess) would be to sum col and amount on the same row:
WITH t(col) AS
(
SELECT 1 FROM dual
UNION
SELECT 2 FROM dual
UNION
SELECT 3 FROM dual
UNION
SELECT 4 FROM dual
UNION
SELECT 5 FROM dual
),
t1(amount, col) AS
(
SELECT 100, 2 FROM dual
UNION
SELECT 200, 3 FROM dual
)
SELECT col,
(SELECT col FROM t WHERE col = outer_q.col) new_col,
(SELECT SUM(all_amount)
FROM
(SELECT col, col + amount all_amount FROM t1)
WHERE col = outer_q.col
) newest_col -- gives 315 as it takes whole `SUM`
FROM t outer_q
WHERE col = 2;

Answer 2

The inner query fails because you tried to push the outer_q.col reference two levels down. Correlated query goes only 1 level down
Reference: http://asktom.oracle.com/pls/asktom/f?p=100:11:0::::P11_QUESTION_ID:1853075500346799932