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Why I am getting year as 0020 instead of 2020 for the

Why I am getting 0020 instead of 2020 for below query.

select to_char(to_date(sysdate,'dd-mm-yyyy'),'iyyy') from dual.

Instead of sysdate if I give date like '5-dec-2020' it's giving correct.

Any ideas why iso value for sysdate year is coming as 0020


  • Jonathan Lewis
    Jonathan Lewis Member Posts: 9,974 Blue Diamond

    Your problem is that you've applied to_date() to sysdate, but sysdate is a DATE, so Oracle has to convert it to a character string using your default date format before applying the to_date() to turn it back into a date.

    select to_char(to_date(sysdate,'dd-mm-yyyy'),'iyyy') from dual;

    turns into

    select to_char(to_date(to_char(sysdate),'dd-mm-yyyy'),'iyyy') from dual;

    But strip out just the to_char() call, and in my system I see:

    SQL> select to_char(sysdate) from dual;

    So your query becomes:

    select to_char(to_date('10-Dec-20','dd-mm-yyyy'),'iyyy') from dual;

    In old versions of Oracle I think this would have crashed because Oracle sees Dec when it would want 12, but in all recent versions of Oracle it works, but you have asked for year 0020, not for year 2020.

    You ought to query

    select to_char(sysdate, 'iyyy') from dual;

    (If you executed: alter session set nls_date_format='dd-mm-yyyy'; before running your query that would work around a problem with pre-existing unchangeable code).


    Jonathan Lewis