Taking union of two lists based on column

Question

I am taking a union of two lists using Linq to Sql. Using List1 and List2:

 var tr = List1.Union(List2).ToList();

Union works fine, but the pro

Answer 1

try somthing this

var List3 = List1.Join(
List2, 
l1 => l1.Id,
l2 => l2.Id,
(l1, l2) => new Model
{
   Id = l1.Id,
   Val1 = l1.Val1 or other,
   Val2 = l2.Val2  or other
});

for more details you can show your model