title: calculation of lapsed time between two entry
body: <p>I have table which records staff's work log. The table columns as staffid,orderid,Startingtime,endingtime etc.I know how to find the difference between two time ie starting and ending time. But I need to know how many minutes lapsing a worker to start another work.
  staffid  workid  Startingtime  endingtime  timetaken
  100       10222    11.30 pm      11.50 pm     20
  100       20122    11.55 pm      01.55 pm     120
  Here i need to calculate how many minutes staff lapsed between two work.(here 5 minutes 11.50pm and 11.55 pm) </p>