Syntax

1. <value_spec> ::=
     <literal>
   | <parameter_spec>
   | NULL
   | USER
   | USERGROUP
   | SYSDBA
   | CURRENT_SCHEMA
   | UID
   | [<schema_name>.]<sequence_name>.NEXTVAL
   | [<schema_name>.]<sequence_name>.CURRVAL
   | <table_name>.CURRVAL
   | DATE
   | TIME
   | TIMESTAMP
   | UTCDATE
   | TIMEZONE
   | UTCDIFF
   | TRUE
   | FALSE
   | TRANSACTION