expression for date difference between current month and previous month

[#1]

Hi All,

Administrator

I want to calculate MTBF in that I want difference between first breakdown of the month and last brekdown of previous date .

But other columns are having expressions monthly then date for previous month won't appear in date field but i want difference

EX :

I am having data like this (INput)

Workcenter   Functional Location     Date                QTY (Expression for the month March)

A                  X                               02/28/2014                      10

B                  Y                              03/12/2014                     20     

C                  Z                              03/20/2014                    30

I want Output like this (I want to show only March data as march is selected in calnder)    

Workcenter   Functional Location     Date                               Difference   QTY (Expression for the month March)

B                  Y                              (03/12/2014-02/28/2014)        12                  20     

C                  Z                              (03/20/2014 -03/12/2014)        8                   30