Enhancements to SQL Date/ Time Arithmetic

Enhancements to SQL Date/ Time Arithmetic

      Structured Query Language (SQL) includes date/time data
types of date, time, and timestamp.  Date/time arithmetic operations
are provided to manipulate values of date/time datatypes.  SQL
date/time arithmetic operations will be added to OS/2* Database
Manager ES 1.0.

      The family of IBM Relational Database Products which supports
SQL Date/Time Arithmetic allows the following operations:
     -  A date can be subtracted from another date, producing a date
duration.
     -  A time can be subtracted from another time, producing a time
duration.
     -  A date can be incremented or decremented by a date duration,
producing a date.
     -  A time can be incremented or decremented by a time duration,
producing a time.
     -  A timestamp can be incremented or decremented by a date or
time duration, producing a timestamp.

      As an extension to the above, the OS/2 Database Manager will
also support manipulation of timestamp values through the following
operations:
     -  A timestamp can be subtracted from another timestamp,
producing a timestamp duration.  This is particularly useful for
deter       mining the time elapsed between operations when a finer
granu       larity of accuracy than seconds is imperative.
        Suppose start_time and end_time are columns of datatype
timestamp.  Then the following example illustrates the use of
timestamp subtraction:
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