A special register is a storage area that is defined
for an application process by database manager and is used to store
information that can be referenced in SQL statements. A reference
to a special register is a reference to a value provided by the current
server. If the value is a string, its CCSID is a default CCSID of
the current server.
The special registers can be referenced as follows:
Notes:
1 The SQL 2003 Core standard uses the form with
the underscore.
The value of these special registers, except
for CURRENT TEMPORAL SYSTEM_TIME, cannot be null.