Query with embedded CURSOR - what is the error? - sql

Question

The following Query Works....
SELECT art.cmp_lvl,
(
CURSOR (
SELECT a.cmp_lvl,
(
CURSOR (
SELECT b.cmp_lvl_code,
b.v1 "R_ST",
b.f_name
FROM temp_data b
WHERE b.cmp_lvl = a.cmp_lvl
ORDER BY SEQ
)
) employee
FROM temp_data a
WHERE a.cmp_lvl = art.cmp_lvl
GROUP BY a.cmp_lvl
)
) g_pos_record
FROM temp_data art
WHERE art.report_name = 'EMP_REPORT'
GROUP BY cmp_lvl
ORDER BY cmp_lvl DESC;
Then I simply add another column name as shown below
SELECT art.cmp_lvl,
art.v1 /*ADDED THIS LINE, SHOWS AN ERROR IN THIS LINE */
(
CURSOR (
SELECT a.cmp_lvl,
a.v1 /*ADDED THIS LINE */
(
CURSOR (
SELECT b.cmp_lvl_code,
b.v1 "R_ST",
b.f_name
FROM temp_data b
WHERE b.cmp_lvl = a.cmp_lvl
AND b.v1 = a.v1 /*ADDED THIS LINE */
ORDER BY SEQ
)
) employee
FROM temp_data a
WHERE a.cmp_lvl = art.cmp_lvl
AND a.v1 = art.v1 /*ADDED THIS LINE */
GROUP BY a.cmp_lvl
)
) g_pos_record
FROM temp_data art
WHERE art.report_name = 'EMP_REPORT'
GROUP BY cmp_lvl
ORDER BY cmp_lvl DESC;
Error: ORA-00904: "ART", "V1": Invalid Identifier
00904. 00000 - "%s: Invalid identifier" "Cause
*Action Error at Line 2
I Cannot figure out why. The column added is in the table (for sure).

Answer 1

You aggregate your data to one result row per cmp_lvl (GROUP BY cmp_lvl). Then you want to show the cmp_lvl's v1. However, as there are multiple rows per cmp_lvl that you are aggregating, which row's v1 shall be shown?
Moreover, there is a comma missing after art.v1.
One solution is to decide for one v1, e.g.:
SELECT art.cmp_lvl,
MAX(art.v1),
...