title: Total Sum of two columns and show in the third Column
body: <p>I have a Three columns in the SQL table,</p>
  
  <p>I want to show the sum of the total of two columns in the third column. How can I show that using SQL query.  </p>
  
  <p>This is my table structure</p>
  
  <pre><code>Id  int Unchecked
  Col_A    int    Unchecked
  Col_B    int    Unchecked
  Total     int   Checked
  </code></pre>