CURRENT DATE
The CURRENT DATE special register specifies a date that is based on a reading of the time-of-day clock when the SQL statement is executed at the current server.
If this special register is used more than one time within a single SQL statement, or used with CURRENT TIME or CURRENT TIMESTAMP within a single statement, all values are based on a single clock reading.1
The value of CURRENT DATE in a user-defined function or stored procedure is inherited according to the rules in Table 1. For other applications, the date is derived by the DB2® that executes the SQL statement that refers to the special register. For a description of how the date is derived, see Datetime special registers.
Specifying CURRENT_DATE is equivalent to specifying CURRENT DATE.
SELECT AVG(YEAR(CURRENT DATE - BIRTHDATE))
FROM DSN8A10.EMP;