title: How to calculate the sum of a column from set of rows based on a condition in gridview?
body: <p>Visit <a href="http://i.stack.imgur.com/pwGF3.png" rel="nofollow">http://i.stack.imgur.com/pwGF3.png</a> </p>
  
  <p>I am new to VB.NET and I want to find the sum of Quantity where BatchIDs are Equal. In this example, answer should be 'PAN-NEW'= 4,VSD-1850=2
  My aim is to check the result with Current Stock before invoicing.
  How to do this in vb.net? Please help me</p>