title: How to compare values of two datatable columns
body: <p>I want to validate quantity columns of two datatable. Given below is the sample datatable. I want to take the sum of the quantity of each item from <strong>dtItems</strong> and compare with the quantity of same item in  <strong>dtMasterItem</strong>. If <strong>dtItems</strong> quantity become greater than <strong>dtMasterItem</strong> quantity then I want show the message like <strong><em>Available quantity is 1000 for itemcode</em></strong></p>
  
  <p><strong><em>dtMasterItem</em></strong></p>
  
  <pre><code>ItemCode      Quantity
  
    A            3000    
    B            5000    
    C            6000 
  </code></pre>
  
  <p><strong>dtItems</strong></p>
  
  <pre><code>ItemCode      Quantity
  
     A           2000
     A           1000
     A           500
     B           3000  
     B           2000  
     C           6000 
  </code></pre>
  
  <p>As per my logic if we validate the above table data the output will be like <strong><em>Available quantity is 3000 for A</em></strong></p>