How to find first occurrence with LINQ

Question

Using .NET LINQ, I'd like to find entries (Name) that start with PID equal to 0 or 1. But if the Name has both, I only want 0. In the following:

PID Name
 0  P1
 1  P1
 1  P3
 0  P4
 0  P5
 1  P5

I'll get back rows:

 0 P1
 1 P3
 0 P4
 0 P5

The PID values can go up to 10. Any suggestions how this can be done?

Answer 1

You can use:

var results = collection
               .Where(item => item.PID == 0 || item.PID == 1)
               .GroupBy(item => item.Name)
               .Select(g => g.OrderBy(item => item.PID).First());

Answer 2

At the end of statement add ".FirstOrDefault()"