ORA-00932: inconsistent datatypes: expected CHAR got NUMBER while adding 1 to a date

Question

Probably a silly mistake, but I couldn't figure this out myself. When I run this query in Oracle 11g.

If this question is answered in SO, please let me know the link.

with LAST_BUSINESS_DAY as (select DECODE(to_char(last_day(to_date('29-mar-2013')), 'D'), 
                                  , '7', to_char((last_day('29-mar-2013') - 1), 'DD-MON-YYYY')
                                  , '1', to_char((last_day('29-mar-2013') - 2), 'DD-MON-YYYY')
                                  , to_char(last_day('29-apr-2013'), 'DD-MON-YYYY')) as LAST_BD from dual),
      HOLIDAYS as (select distinct rpt_day
                     from rpt_days rpt left join
                          calendars cal on rpt.calendar_id = cal.calendar_id
                    where rpt.type = 2 
                      and cal.group = 4)
  select case when to_char(to_date(LAST_BD, 'DD-MON-YYYY'), 'D') is null
              then LAST_BD
              else DECODE(to_char(to_date(LAST_BD, 'DD-MON-YYYY') , 'D')
                          , '6', LAST_BD
                          , '2', LAST_BD
                          , LAST_BD)
         end as LAST_BD_OF_MONTH
    from LAST_BUSINESS_DAY LBD 
         inner join HOLIDAYS H on LBD.LAST_BD = H.rpt_day

I get the result as

LAST_BD_OF_MONTH
===================
29-MAR-2013

Now, when I try to add a day to the LAST_BD date, it throws an error.

with LAST_BUSINESS_DAY as (select DECODE(to_char(last_day(to_date('29-mar-2013')), 'D'), 
                                  , '7', to_char((last_day('29-mar-2013') - 1), 'DD-MON-YYYY')
                                  , '1', to_char((last_day('29-mar-2013') - 2), 'DD-MON-YYYY')
                                  , to_char(last_day('29-apr-2013'), 'DD-MON-YYYY')) as LAST_BD from dual),
      HOLIDAYS as (select distinct rpt_day
                     from rpt_days rpt left join
                          calendars cal on rpt.calendar_id = cal.calendar_id
                    where rpt.type = 2 
                      and cal.group = 4)
  select case when to_char(to_date(LAST_BD, 'DD-MON-YYYY'), 'D') is null
              then LAST_BD
              else DECODE(to_char(to_date(LAST_BD, 'DD-MON-YYYY') , 'D') -- line 35
                          , '6', LAST_BD - 1 -- CHANGED THIS
                          , '2', LAST_BD + 1 -- CHANGED THIS
                          , LAST_BD)
         end as LAST_BD_OF_MONTH
    from LAST_BUSINESS_DAY LBD 
         inner join HOLIDAYS H on LBD.LAST_BD = H.rpt_day

Error Message

ORA-00932: inconsistent datatypes: expected CHAR got NUMBER
00932. 00000 - "inconsistent datatypes: expected %s got %s" *Cause:
*Action: Error at Line: 35 Column: 20

As I said, this might be a simple overlook from my side. I tried converting the LAST_BD to a date, but didn't work.

I tried changing the DECODE as below

case when to_char(to_date(LAST_BD, 'DD-MON-YYYY'), 'D') is null
     then LAST_BD
     else DECODE(to_char(to_date(LAST_BD, 'DD-MON-YYYY') , 'D')
                 , '6', to_date(LAST_BD, 'DD-MON-YYYY') - 1
                 , '2', LAST_BD + 1 -- line 37
                 , LAST_BD)
end as LAST_BD_OF_MONTH

and got this error :

ORA-00932: inconsistent datatypes: expected DATE got NUMBER
00932. 00000 - "inconsistent datatypes: expected %s got %s" *Cause:
*Action: Error at Line: 37 Column: 42

So, I changed the line 37 to this,

case when to_char(to_date(LAST_BD, 'DD-MON-YYYY'), 'D') is null
     then LAST_BD
     else DECODE(to_char(to_date(LAST_BD, 'DD-MON-YYYY') , 'D')
                , '6', to_date(LAST_BD, 'DD-MON-YYYY') - 1
                , '2', to_date(LAST_BD, 'DD-MON-YYYY') + 1
                , LAST_BD)
end as LAST_BD_OF_MONTH

and this time its a different message.

ORA-00932: inconsistent datatypes: expected CHAR got DATE
00932. 00000 - "inconsistent datatypes: expected %s got %s" *Cause:
*Action: Error at Line: 35 Column: 20

Any help to get this corrected is greatly appreciated.

ANSWER :

with LAST_BUSINESS_DAY as (select DECODE(to_char(last_day(to_date('29-mar-2013')), 'D'), 
                                  , '7', to_char((last_day('29-mar-2013') - 1), 'DD-MON-YYYY')
                                  , '1', to_char((last_day('29-mar-2013') - 2), 'DD-MON-YYYY')
                                  , to_char(last_day('29-apr-2013'), 'DD-MON-YYYY')) as LAST_BD from dual),
      HOLIDAYS as (select distinct rpt_day
                     from rpt_days rpt left join
                          calendars cal on rpt.calendar_id = cal.calendar_id
                    where rpt.type = 2 
                      and cal.group = 4)
  select case when to_char(to_date(LAST_BD, 'DD-MON-YYYY'), 'D') is null
              then LAST_BD
              else DECODE(to_char(to_date(LAST_BD, 'DD-MON-YYYY') , 'D')
                          , '6', to_char (to_date(LAST_BD, 'DD-MON-YYYY') - 1, 'DD-MON-YYYY')
                          , '2', to_char (to_date(LAST_BD, 'DD-MON-YYYY') + 1, 'DD-MON-YYYY')
                          , LAST_BD)
         end as LAST_BD_OF_MONTH
    from LAST_BUSINESS_DAY LBD 
         inner join HOLIDAYS H on LBD.LAST_BD = H.rpt_day

Answer 1

So do I see it right, that you converted LAST_BDfrom VARCHAR2 to DATE (due to):

to_date(LAST_BD, 'DD-MON-YYYY') 

In the second query you try to subtract 1 from this VARCHAR2:

LAST_BD - 1

This won't work. As a consequence you get the error:

ORA-00932: inconsistent datatypes: expected CHAR got NUMBER

What would probably work is, if you convert it to DATE, add 1 and convert it back to VARCHAR2

with LAST_BUSINESS_DAY as (select DECODE(to_char(last_day(to_date('29-mar-2013')), 'D'), 
                                  , '7', to_char((last_day('29-mar-2013') - 1), 'DD-MON-YYYY')
                                  , '1', to_char((last_day('29-mar-2013') - 2), 'DD-MON-YYYY')
                                  , to_char(last_day('29-apr-2013'), 'DD-MON-YYYY')) as LAST_BD from dual),
      HOLIDAYS as (select distinct rpt_day
                     from rpt_days rpt left join
                          calendars cal on rpt.calendar_id = cal.calendar_id
                    where rpt.type = 2 
                      and cal.group = 4)
  select case when to_char(to_date(LAST_BD, 'DD-MON-YYYY'), 'D') is null
              then LAST_BD
              else DECODE(to_char(to_date(LAST_BD, 'DD-MON-YYYY') , 'D') -- line 35
                     , '6', to_char (to_date(LAST_BD, 'DD-MON-YYYY') - 1, 'DD-MON-YYYY') 
                     , '2', to_char (to_date(LAST_BD, 'DD-MON-YYYY') + 1, 'DD-MON-YYYY') 
                          , LAST_BD)
         end as LAST_BD_OF_MONTH
    from LAST_BUSINESS_DAY LBD 
         inner join HOLIDAYS H on LBD.LAST_BD = H.rpt_day

Note that the conversion back to VARCHAR2 is required, because DECODE allows only values of one type.

Answer 2

The issue is that DECODE expects a CHAR argument of some kind and LAST_BD + 1 and even the TO_DATE(LAST_BD... return a NUMBER and a DATE respectively.

The following SQL Fiddle demonstrate how to fix this.

http://sqlfiddle.com/#!4/8ac4a3/9

Here is the query:

with LAST_BUSINESS_DAY as (select DECODE(to_char(last_day(to_date('29-mar-2013')), 'D')
                                  , '7', to_char((last_day('29-mar-2013') - 1), 'DD-MON-YYYY')
                                  , '1', to_char((last_day('29-mar-2013') - 2), 'DD-MON-YYYY')
                                  , to_char(last_day('29-apr-2013'), 'DD-MON-YYYY')) as LAST_BD from dual),
      HOLIDAYS as (select distinct reporting_day
                     from tbm_reporting_days trdy left join
                          tbm_calendars tcal on trdy.calendar_id = tcal.calendar_id
                    where trdy.type = 2 
                      and tcal.site_id = 4)
  select case when to_char(to_date(LAST_BD, 'DD-MON-YYYY'), 'D') is null
              then LAST_BD
              else DECODE(to_char(to_date(LAST_BD, 'DD-MON-YYYY') , 'D')
                          , '6', TO_CHAR(
                              (TO_DATE(LAST_BD, 'DD-MON-YYYY') - 1), 'D')
                          , '2', TO_CHAR(
                              (TO_DATE(LAST_BD, 'DD-MON-YYYY') - 1), 'D')
                          , LAST_BD)
         end as LAST_BD_OF_MONTH
    from LAST_BUSINESS_DAY LBD 
         inner join HOLIDAYS H on LBD.LAST_BD = H.reporting_day

You have to convert the number or date back to a CHAR with TO_CHAR.