DBMS compliance with SQL-92 datetime/interval operators and functions is spotty, so this section is meant to be used as a reference. DBMSes have their own extended operators and functions that perform date and time arithmetic. For information about datetime and interval data types, see “Datetime Types” and “Interval Types” in Chapter 3.
Use the same operators introduced in “Performing Arithmetic Operations” earlier in this chapter to perform datetime and interval arithmetic. The common temporal operations are:
Subtracting two dates to calculate the interval between them
Adding or subtracting an interval and ...