title: Mysql query to find sum of fields with same column value
body: <p>I have a table like this</p>
  
  <pre><code>id |  invent_id         |   order
   1 | 95948214           | 70
   2 | 46018572           | 30
   3 | 46018572           | 20
   4 | 46018572           | 50
   5 | 36025764           | 60
   6 | 36025764           | 70
   7 | 95948214           | 80
   8 | 95948214           | 90
  </code></pre>
  
  <p>I want get the sum of order qty with same invent id</p>
  
  <p>That is the want the result like this</p>
  
  <pre><code>   |  invent_id         |   order
     | 95948214           | 240
     | 46018572           | 100
     | 36025764           | 130
  </code></pre>
  
  <p>how can we write the mysql query</p>