title: What query should I write to calculate the cumulative salary of employees from the salary table
body: <p>A salary table is given and we need to write a single query which prints the cumulative salary of employees.
  For Example:</p>
  
  <pre><code>Emp  Sal
  A    10
  B    15
  C    20
  D    5
  
  
  OutPut:
  
  Emp  Sal   Cum_Sal
  A    10      10
  B    15      25
  C    20      45
  D    5       50
  </code></pre>