title: Found Duplicate record in excel sheet using c# .net
body: <p>I've a datatable that has been filled by excel sheet, it has lots of product id's and some other data. I want to check if there is any duplicate product id in my datatable and tell user that these prodcuts ids are duplicates or something like that.</p>
  
  <p>Lmbda, Linq , Looping anything will do.</p>
  
  <p>Thanks</p>