ORA-01843: not a valid month : TO_DATE('12-JUN-02','DD-MON-YY')

Question

I've faced a problem during insert. Here is the problem:

INSERT INTO SALES_ORDER_A4 (ORDERNO , CLIENTNO , ORDERDATE , DELYADDR , SALESMANNO , DELYTYPE , BILLYN , DELYDATE, ORDERSTATUS)
SELECT 'O19008' ,
       'C00005' ,
       to_date('24-MAY-02','DD-MON-YY'),
       'Delhi' ,
       'S00004' ,
       'F' ,
       'N' ,
       to_date('26-MAY-02','DD-MON-YY') ,
       'In Process'
FROM DUAL
UNION ALL
SELECT 'O19001' ,
       'C00001' ,
       to_date('12-JUN-02','DD-MON-YY') ,
       'Delhi' ,
       'S00001' ,
       'F' ,
       'N' ,
       to_date('20-JUN-02','DD-MON-YY') ,
       'In Process'
FROM DUAL
UNION ALL
SELECT 'O19002' ,
       'C00002' ,
       to_date('25-JUN-02','DD-MON-YY'),
       'Delhi' ,
       'S00002' ,
       'P' ,
       'N' ,
       to_date('27-JUL-02','DD-MON-YY') ,
       'Cancelled'
FROM DUAL

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I have faced an exception at phrase *to_date('12-JUN-02','DD-MON-YY' )* that:

ORA-01843: not a valid month

My instructor can not find the problem, what is the problem here?

Answer 1

This is mostly because NLS_DATE_LANGUAGE is not set correctly.

First check the value by:

select * from v$nls_parameters where parameter like '%DATE%'

If the value of NLS_DATE_LANGUAGE is not American then change it by:

alter session set nls_date_language='American';

And try again.