Oracle 10g Time Zone Confusion

Question

SELECT TO_CHAR(SYSDATE, \'YYYY-MM-DD HH24:MI\')
      ,TO_CHAR(CURRENT_DATE, \'YYYY-MM-DD HH24:MI\')
      ,TO_CHAR(SYSTIMESTAMP, \'YYYY-MM-DD HH24:MI TZR\') 
               


        

Answer 1

Use UTC time and offset your timezone from UTC, To get UTC in Oracle use SYS_EXTRACT_UTC

Convert SYSTEMDATE to UTC

    select sys_extract_utc(systimestamp) from dual;

As for the difference the definition from Oracle documentation might help to explain:

• LOCALTIMESTAMP returns the current date and time in the session time zone in a value of datatype TIMESTAMP
• CURRENT_TIMESTAMP returns the current date and time in the session time zone, in a value of datatype TIMESTAMP WITH TIME ZONE
• SYSTIMESTAMP returns the system date, including fractional seconds and time zone, of the system on which the database resides
• CURRENT_DATE returns the current date in the session time zone, in a value in the Gregorian calendar of datatype DATE.
• SYSDATE returns the current date and time set for the operating system on which the database resides.
• DBTIMEZONE returns the value of the database time zone.