How does the client obtain the server time?

If you only get the date
Select current_date from sysibm. sysdummy1 or
Select curdate () from sysibm. sysdummy1

If you only get the time and the time precision is in seconds
Select current_time from sysibm. sysdummy1 or
Select curtime () from sysibm. sysdummy1
You can get the time

To be accurate to milliseconds or microseconds
Select current_timestamp from sysibm. sysdummy1
The obtained value is 2005-12-20-16.41.59.961520.

Sysibm. sysdummy1 is a table with only one row of records and belongs to the system table.
Usually similar to Oracle dual
Oracle usage
8i
Select to_char (sysdate, 'yyyy-mm-dd hh24: MI: ss') from dual can only be obtained in seconds
9i
Select systimestamp from dual; milliseconds can be obtained

SQL Server does not need to. You only need to select getdate () to obtain the millisecond.