应用 TO_DATE 时，连接的选择列表值返回“无效月份”

Question

I have month and year values from select list, concatenated them in a string. If TO_DATE is applied on the string, that returns 'not a valid month' error. Below is my code snippet,

V_DATE_FROM_STR_TEST := TRIM('01-'||TRIM(TO_CHAR(:P3_FROM_MONTH))||'-'||TRIM(TO_CHAR(:P3_YEAR)));

V_DATE_TO_STR_TEST := TRIM('01-'||TRIM(TO_CHAR(:P3_TO_MONTH))||'-'||TRIM(TO_CHAR(:P3_YEAR)));

Error 'not a valid month' occurs on this line,

TRUNC(TO_DATE(V_DATE_FROM_STR_TEST, 'DD-MON-YYYY'))

I have tried printing by HTP.PRN(V_DATE_FROM_STR_TEST) that shows date 01-JAN-2020 .

Adding LOVs

Month LOV

select to_char(add_months(trunc(sysdate, 'yyyy'), level - 1), 'MONTH') d, 
to_char(add_months(trunc(sysdate, 'yyyy'), level - 1), 'MON') r
  from dual
connect by level <= 12

Year LOV

    select YEAR d, YEAR r
from   (select to_number(to_char(sysdate,'yyyy')) -8 YEAR
from dual
UNION
select to_number(to_char(sysdate,'yyyy')) -7 YEAR
from dual
UNION
select to_number(to_char(sysdate,'yyyy')) -6 YEAR
from dual
UNION
select to_number(to_char(sysdate,'yyyy')) -5 YEAR
from dual
UNION
select to_number(to_char(sysdate,'yyyy')) -4 YEAR
from dual
UNION
select to_number(to_char(sysdate,'yyyy')) -3 YEAR
from dual
UNION
select to_number(to_char(sysdate,'yyyy')) -2 YEAR
from dual
UNION
select to_number(to_char(sysdate,'yyyy')) -1 YEAR
from dual
UNION
select to_number(to_char(sysdate,'yyyy')) YEAR
from dual
) order by year desc

I am guessing there are some unwanted character is added in the date string from select list value, how can I remove that?

Answer 1

If you switch to digits, things might improve.

Month LoV: display words , but return numbers :

select to_char(add_months(trunc(sysdate, 'yyyy'), level - 1), 'MONTH') d, 
       level r
  from dual
connect by level <= 12;

Then use this for the resulting string:

to_date(lpad(:P3_FROM_MONTH, 2, '0') || :P3_YEAR, 'mmyyyy')

---

Also, all those TRIM s look unnecessary, but OK - I understand - you tried to fix the problem.

Answer 2

While not directly referenced you can simplify your "Year LOV" query.

select yr d, yr r
  from ( select extract(year from sysdate)-level +1 yr
           from dual 
          connect by level <= 9
       )
 order by yr desc;