ESQL/C: Difficulties with DECLARE CURSOR and nested FROM CLAUSE

Question

Hello @All,
i am trying to migrate an old esql-c-Application to Oracle 11g (on 64-Bit-AIX 7.1 - Platform)
PreCompiling is OK, but during runtime the following DECLARE - Statement returns ORA-01001: invalid cursor :
EXEC SQL
DECLARE cur_xyz CURSOR FOR
SELECT vPE, mPE, mZW, COUNT (*)
FROM ( SELECT v.K_PE AS vPE, m.K_PE AS mPE, m.ZW AS mZW, v.VKG
FROM ( SELECT K_NR, K_PE, u3.VKG, POS
FROM u3, r
WHERE u3.K_NR = '999999'
AND     u3.LANG = 'F'
AND SUBSTR (PRTCTRL, 5, 1) > '0'
AND u3.VKG = r.VKG ( + )
) v, m
WHERE
v.K_NR = m.K_NR ( + )
AND v.K_PE = m.K_PE ( + )
AND POS is Null
) X
WHERE not EXISTS (SELECT VKG FROM NP WHERE X.VKG = NP.VKG )
GROUP BY vPE, mPE, mZW
ORDER BY vPE
When I run this statement without "EXEC SQL DECLARE cur_xyz CURSOR FOR" in SQL-Developer, there is no problem.
What is my fault? I hope, that I don't have to redesign this.
Thx in advance for anyonce help.

Answer 1

Hey Billy,
I work in a C/C++-Environment under AIX. I allready build a library with with more than x.000 Functions with ESQL-Statements.
Most of them are running.
If I need a CURSOR, I allways use constructs like this:
EXEC SQL DECLARE CursorName [SCROLL]CURSOR FOR
SELECT ...
if (SQLC == 0) {
EXEC SQL OPEN CursorName;
while (SQLC == 0) {
EXEC SQL FETCH ... CursorName INTO :<Structure or Fieldlist>;
EXEC SQL CLOSE CursorName;
At the Moment, I don't work with a cursor-variable in the DECLARE-Section.
In the case i discribed above, it is the first, where the ORA-01001 occurs.
Is it necessary to work with SQL_CURSOR - Variable in all or in special cases?
Thx 4 answers.