title: How to check the overlapping time intervals from one type 2 SCD dimension
body: <p>I have one problem identifying and fixing some records having overlapping time intervals, for one scd type 2 dimension.
     What I have is:</p>
  
  <pre><code>Bkey   Uid  startDate                       endDate
  'John'  1   1990-01-01 (some time stamp)    2017-01-10 (some time stamp)
  'John'  2   2016-11=03 (some time stamp)    2016-11-14 (some time stamp)
  'John'  3   2016-11-14 (some time stamp)    2016-12-29 (some time stamp)
  'John'  4   2016-12-29 (some time stamp)    2017-01-10 (some time stamp)
  'John'  5   2017-01-10 (some time stamp)    2017-04-22 (some time stamp)
  ......
  </code></pre>
  
  <p>I want to find (first) which are all the Johns having overlapping time periods, for a table having lots and lots of Johns and then to figure out a way to correct those overlapping time periods. For the latest I know there are some function LAGG, LEAD, which can handle that, but it eludes me how to find those over lappings.
  Any hints?
  Regards,</p>