title: LINQ to DataSet, distinct by multiple columns
body: <p>Just wanted to check if there is way to do distinct by multiple columns. Thanks in advance!!!</p>
  
  <p>BTW, I found a great LINQ extension <a href="https://stackoverflow.com/questions/520030/why-is-there-no-linq-method-to-return-distinct-values-by-a-predicate/520046#520046">here</a> but need some guidance to use it for multiple columns</p>