Rewriting long cursor - oracle

Question

I have the following long cursor.
CURSOR curWeek IS SELECT DECODE(TO_CHAR(TO_DATE( "1", 'dd.mm.yyyy'), 'dy'), 'mo', 'KW ' || TO_CHAR(TO_DATE( "1", 'dd.mm.yyyy'), 'ww'), null),
.
.
.
DECODE(TO_CHAR(TO_DATE("31", 'dd.mm.yyyy'), 'dy'), 'mo', 'KW ' || TO_CHAR(TO_DATE("31", 'dd.mm.yyyy'), 'ww'), null)
FROM (SELECT ROWNUM AS SP, TO_CHAR(myFrom + ROWNUM - 1, 'dd.mm.yyyy') AS DATUM
FROM MY_CAL
WHERE ROWNUM < TO_NUMBER( ADD_MONTHS( myFrom , 1) - 1, 'j')) - TO_NUMBER(TO_CHAR(myFrom, 'j')) + 2)
PIVOT(MAX(DATUM) FOR SP IN (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31));
Now Im trying to rewrite it. I try to use a loop like the following:
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
PROCEDURE PB_HELPER (myIndex IN BINARY_INTEGER, myFrom IN DATE) IS
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
sqlCommand VARCHAR2(32000);
curWeek SYS_REFCURSOR;
BEGIN
sSqlCommand := 'SELECT ';
FOR i IN 1..31
LOOP
sqlCommand := sqlCommand || 'DECODE(TO_CHAR(TO_DATE( "'||i||'" , ''dd.mm.yyyy''), ''dy''), ''mo'', ''KW'' || TO_CHAR(TO_DATE( "'||i||'" , ''dd.mm.yyyy''), ''ww''), null),';
END LOOP;
sqlCommand := RTRIM(sqlCommand, ',');
sqlCommand := sqlCommand || ' FROM (SELECT ROWNUM AS SP, TO_CHAR(' || myFrom || '+ ROWNUM - 1, ''dd.mm.yyyy'') AS DATUM
FROM MY_CAL
WHERE ROWNUM < TO_NUMBER(TO_CHAR(ADD_MONTHS('|| myFrom ||', 1) - 1, ''j'')) - TO_NUMBER(TO_CHAR('|| myFrom ||', ''j'')) + 2)
PIVOT(MAX(DATUM) FOR SP IN (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31))';
OPEN curWeek FOR sqlCommand USING myFrom;
CLOSE curWeek;
END PB_HELPER;
However it doesn't work. I'm getting ORA-00907 error. Anyone could help?
Thanks in advance!

Answer 1

Do not do this; it does not simplify the query, in fact it makes it vastly more complicated. Your query appears long, but that is just a function of the number of columns, not complexity. It is a simple query. Building a function to create it dynamically is much more difficult to understand, modify (when required), more error prone, and will run slower. That all said, there is (imho) a benefit to remove a long query entirely from the base line code. (I only need to look at it if I suspect an error or it requires maintenance.) This can be bone by hiding it in a package spec.
create or replace package curweek_cursor_pkg as
cursor curweek is
select decode(to_char(to_date( "1", 'dd.mm.yyyy'), 'dy'), 'mo', 'KW ' || to_char(to_date( "1", 'dd.mm.yyyy'), 'ww'), null),
.
.
.
decode(to_char(to_date("31", 'dd.mm.yyyy'), 'dy'), 'mo', 'KW ' || to_char(to_date("31", 'dd.mm.yyyy'), 'ww'), null)
from (select rownum as sp, to_char(myfrom + rownum - 1, 'dd.mm.yyyy') as datum
from my_cal
where rownum < to_number( add_months( myfrom , 1) - 1, 'j')) - to_number(to_char(myfrom, 'j')) + 2)
pivot(max(datum) for sp in (1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31));
end curweek_cursor_pkg;
Then in base code reference it as package_name.cursor_name. So curweek_cursor_pkg.curweek; (see demo)