title: remove duplicates in column TSQL
body: <p>wondering anyone could help me please.
  I have date output from a Stored Procedure something like this:</p>
  
  <pre><code>Year    AccountName Certs   MoreCerts
  2015    Rosy        3650097   444455
  2015    Rosy        3650097   5645665
  2015    Rosy        3650097    4544
  2015    Rosy        3650097   33423
  2015    Rosy        3650097    232454
  2014    Rosy        112379     6767878
  2014    Rosy    112379  68878
  2014    Rosy    112379  567
  2014    Rosy    112379  567
  2014    Rosy    112379  4567
  2014    Rosy    112379  345667
  2015    John    12000   23456
  2015    John    12000   23345
  2015    John    12000   2111
  2015    John    12000   456
  2014    John    50000   887
  2014    John    50000   43432
  2014    John    50000   2333
  </code></pre>
  
  <p>and I would like to have like this i.e remove duplicate values from Certs columns while retain everything else in table as it is</p>
  
  <pre><code>Year    AccountName Certs        MoreCerts
  2015    Rosy         3650097      444455
  2015    Rosy                      5645665
  2015    Rosy                      4544
  2015    Rosy                      33423
  2015    Rosy                      232454
  2014    Rosy         112379       6767878
  2014    Rosy                      68878
  2014    Rosy                       567
  2014    Rosy                       567
  2014    Rosy                       4567
  2014    Rosy                       345667
  2015    John         12000         23456
  2015    John                       23345
  2015    John                       2111
  2015    John                       456
  2014    John         50000         887
  2014    John                       43432
  2014    John                       2333
  </code></pre>
  
  <p>tried row_number and sub select etc. but cant figure out. 
  any help pls?</p>