A VARCHAR containing the external representation.
Converts the local datetime to GMT and returns its external representation as a string.
We are at central european time zone CET(GMT+1).
SQL> use Demo;
Done. -- 3 msec.
SQL> select (datestring_GMT (stringdate ('2000-01-01 22:00')));
callret
VARCHAR
_______________________________________________________________________________
2000-01-01 21:00:00.000000
1 Rows. -- 45 msec.
The discussion of TIMESTAMP datatype in section Database Concepts of the documentation.