title: Multiple column sum and update total field [MySQL]
body: <p>I have table named 'spending_list'.</p>
  
  <pre><code> id , food,  tea,  snack, others, coffee, total 
  
   1  , 8000 , 0,    0,     1500,   4400,   0
  
   2  , 0 ,    4000, 500,   0,      1500,   0
  </code></pre>
  
  <p>I want to insert total field  using sum ( food + tea + snack + others + coffee).</p>
  
  <p>I don't know how can make SQL operators.</p>