CREATE OR REPLACE VIEW VCOMCD_CLM AS
SELECT -- Comptes
J.NMINT
FROM
COMCRG X,
COMTRA T,
COMTLC U,
COMPRF P,
TYMCOM C,
COMCRD D,
INTERV J,
COMCRA A,
COMCRE E
WHERE
T.NOTCO=X.NOTCO AND
U.CTLCO=X.CTLCO AND
P.NPRFT=T.NPRFT AND
C.CTCOM=P.CTCOM AND
C.COLAN=U.COLAN AND
D.NOLCO=X.NOLCO AND
A.NOECO=D.NOECO AND
E.NOECO=D.NOECO AND
J.COINT=D.CODES AND
D.CTDES='K'
UNION ALL
SELECT
TO_NCHAR(NULL)
FROM
DUAL

ORA-12714: jeu de caractères national indiqué non valide

SELECT TO_NCHAR(NULL)FROM DUAL

ORA-12714: invalid national character set specified
 *Cause: Only UTF8 and AL16UTF16 are allowed to be used as the national
         character set
 *Action: Ensure that the specified national character set is valid

Name   Type          Nullable Default Comments 
------ ------------- -------- ------- -------- 
COINT  VARCHAR2(11)                            
CTINT  VARCHAR2(1)                             
NMINT  NVARCHAR2(30) Y                         
LICIV  VARCHAR2(20)  Y                         
ADINT1 NVARCHAR2(30) Y                         
ADINT2 NVARCHAR2(30) Y                         
ADINT3 NVARCHAR2(30) Y                         
ADINT4 NVARCHAR2(30) Y                         
COLAN  VARCHAR2(1)                             
COTAX  VARCHAR2(1)   Y                         
CREFI  VARCHAR2(2)   Y                         
COCAI  VARCHAR2(1)   Y                         
NUCPT  VARCHAR2(8)   Y                         
NBJDP  NUMBER(1)     Y                         
NUBNK  VARCHAR2(23)  Y                         
NMFRA  VARCHAR2(30)  Y                         
NMANG  VARCHAR2(30)  Y                         
NMHOL  VARCHAR2(30)  Y                         
NMESP  VARCHAR2(30)  Y                         
NMITA  VARCHAR2(30)  Y                         
CLINT  VARCHAR2(2)   Y                         
COSIE  VARCHAR2(5)   Y                         
NUTEL  VARCHAR2(100) Y                         
NUTLX  VARCHAR2(100) Y                         
NUFAX  VARCHAR2(100) Y                         
COECO  VARCHAR2(3)   Y                         
COJUR  VARCHAR2(2)   Y                         
CPTIT  VARCHAR2(8)   Y                         
CIINT  VARCHAR2(13)  Y                         
NOSIR  VARCHAR2(13)  Y                         
CDICP  VARCHAR2(1)   Y                         
CCOMP  VARCHAR2(1)   Y                         
SURFA  VARCHAR2(1)                             
NRECO  NUMBER(1)     Y                         
CCONG  VARCHAR2(1)   Y                         
CTCCO  VARCHAR2(1)   Y                         
CSINT  VARCHAR2(1)   Y                         
INTAC  VARCHAR2(1)   Y                         
CPISO  VARCHAR2(2)   Y                         
COCNV  VARCHAR2(1)   Y                         
CDVCV  VARCHAR2(3)   Y                         
NMGER  VARCHAR2(30)  Y                         
EMAIL  VARCHAR2(100) Y                         
CBUFI  VARCHAR2(25)  Y                         
NUENR  VARCHAR2(30)  Y                         
CDPBN  VARCHAR2(2)   Y                         
NMGRE  VARCHAR2(30)  Y                         
COING  VARCHAR2(11)  Y                         
COCGP  VARCHAR2(1)   Y                         
DASYS  DATE                                    
COINF  VARCHAR2(8)   Y                         
FXRAC  VARCHAR2(1)   Y                         
ADINT5 NVARCHAR2(30) Y                         
CDVRF  VARCHAR2(3)   Y                         
NINT2  NVARCHAR2(30) Y                         
CONAS  NUMBER(9)     Y                         
COTIN  VARCHAR2(9)   Y                         
STTQI  VARCHAR2(1)   Y                         
RGCOD  VARCHAR2(2)   Y                         
RGREF  VARCHAR2(5)   Y                         
RISET  NUMBER(6)     Y                         
TYPNG  VARCHAR2(3)   Y                         
CCAME  VARCHAR2(1)   Y                         
FACCL  VARCHAR2(1)   Y                         
CCOTH  VARCHAR2(1)   Y                         
CORIG  VARCHAR2(20)  Y                         
PORIG  NUMBER(6)     Y                         
DACRE  DATE                                    
IDINT  NUMBER(10)                              
IDETY  NUMBER(10)    Y                         
RGCID  NUMBER(3)     Y                         
DAOUV  DATE          Y                         
DAFER  DATE          Y                         
CPTTI  VARCHAR2(21)  Y                         
CMPTY  VARCHAR2(1)   Y                         
TAXDF  VARCHAR2(1)   Y                         
DABIR  DATE          Y                         
COUTI  VARCHAR2(8)   Y                         
MGMIN  NUMBER(8)     Y                         
MGPER  VARCHAR2(1)   Y                         
MGPED  NUMBER(2)     Y                         
MGFTR  VARCHAR2(1)   Y                         
NRGMC  VARCHAR2(1)   Y                         
FDTRF  VARCHAR2(1)   Y                         
ACVCD  VARCHAR2(1)   Y        'N'              
CLMCM  VARCHAR2(3)   Y                         
MGMMB  NUMBER(8)     Y                         
CLOPS  VARCHAR2(1)   Y                         
CLRTY  NUMBER(1)     Y                         
COPNR  VARCHAR2(20)  Y                         
EXDLY  VARCHAR2(1)   Y        'N'              
EXMLY  VARCHAR2(1)   Y        'N'              
EXYLY  VARCHAR2(1)   Y        'N'              
LOGOC  VARCHAR2(80)  Y                         
FACOP  VARCHAR2(1)   Y        'N'              
FACOA  VARCHAR2(1)   Y        'N' 

select property_value 
from database_properties 
where property_name = 'NLS_NCHAR_CHARACTERSET'
/
SELECT TO_NCHAR(NULL) FROM DUAL
/
SELECT J.NMINT FROM INTERV J WHERE ROWNUM = 1
/
SELECT J.NMINT FROM INTERV J WHERE ROWNUM = 1
UNION ALL
SELECT TO_NCHAR(NULL) FROM DUAL
/

select property_value
  2  from database_properties
  3  where property_name = 'NLS_NCHAR_CHARACTERSET'
  4  /

PROPERTY_VALUE
--------------------------------------------------------------------------------
AL16UTF16

SQL> SELECT TO_NCHAR(NULL) FROM DUAL
  2  /

TO_NCHAR(NULL)
--------------

SQL> SELECT J.NMINT FROM INTERV J WHERE ROWNUM = 1
  2  /

NMINT
------------------------------------------------------------
Gestionnaire_recettes

SQL> SELECT J.NMINT FROM INTERV J WHERE ROWNUM = 1
  2  UNION ALL
  3  SELECT TO_NCHAR(NULL) FROM DUAL
  4  /

NMINT
------------------------------------------------------------
Gestionnaire_recettes

create view aa_toto as
SELECT J.NMINT FROM INTERV J WHERE ROWNUM = 1
UNION ALL
SELECT TO_NCHAR(NULL) FROM DUAL;

create view aa_toto2 as
SELECT TO_NCHAR(NULL) toto FROM DUAL
UNION ALL
SELECT J.NMINT FROM INTERV J WHERE ROWNUM = 1
;

desc aa_toto 
select object_type from user_objects where object_name='INTERV';

SQL> desc aa_toto
Name  Type          Nullable Default Comments 
----- ------------- -------- ------- -------- 
NMINT NVARCHAR2(60) Y      

select object_type from user_objects where object_name='INTERV';

SQL> select object_type from user_objects where object_name='INTERV';

OBJECT_TYPE
-------------------
TABLE

select object_type from user_objects where object_name='AA_TOTO';

select object_type from user_objects where object_name='AA_TOTO';

OBJECT_TYPE
-------------------
VIEW

Select s.parameter, s.value "SESSION", d.value "DB"
from v$nls_parameters s, nls_database_parameters d
where d.parameter (+) = s.parameter
  and s.parameter = 'NLS_CHARACTERSET';

declare
  last_val varchar2(100);
  x_chset exception;
  pragma exception_init (x_chset, -12714);
begin
  for rec in (select NMINT from aa_toto order by 1) loop
    last_val := convert(rec.NMINT,'<your database charset>','AL16UTF16') ;
  end loop;
exception 
  when x_chset then 
    dbms_output.put_line('last value: '||last_val);
end;
/

SQL> Select s.parameter, s.value "SESSION", d.value "DB"
  2  from v$nls_parameters s, nls_database_parameters d
  3  where d.parameter (+) = s.parameter
  4    and s.parameter = 'NLS_CHARACTERSET';

PARAMETER        SESSION      DB
---------------- ------------ ------------
NLS_CHARACTERSET WE8ISO8859P1 WE8ISO8859P1

declare
  last_val varchar2(100);
  x_chset exception;
  pragma exception_init (x_chset, -12714);
begin
  for rec in (select NMINT from aa_toto order by 1) loop
    last_val := convert(rec.NMINT,'WE8ISO8859P1','AL16UTF16') ;
  end loop;
exception
  when x_chset then
    dbms_output.put_line('last value: '||last_val);
end;

ORA-06550: Ligne 6, colonne 21 :
PL/SQL: ORA-12714: jeu de caractères national indiqué non valide
ORA-06550: Ligne 6, colonne 14 :
PL/SQL: SQL Statement ignored
ORA-06550: Ligne 7, colonne 25 :
PLS-00364: utilisation de variable d'index boucle 'REC' invalide
ORA-06550: Ligne 7, colonne 5 :
PL/SQL: Statement ignored