title: computing 2 column of a table and updating the third column based on distinct value of a table column
body: <pre><code>update tbl_addemployee set 
  amount_due=amount_due+((tsalary/30)*187),
  com_salary_date='2016-11-04' 
  where (forUser='sun4269' and E_id)
  </code></pre>
  
  <p>i want to update com_salary_date for each distinct record where forUser='sun4269'
  and the distinct column name is E_id</p>