This is not the best practice in .NET framework (4 & +) to check equality
String.Compare(x.Username, (string)drUser["Username"],
StringComparison.OrdinalIgnoreCase) == 0
Use the following instead
String.Equals(x.Username, (string)drUser["Username"],
StringComparison.OrdinalIgnoreCase)
- Use an overload of the String.Equals method to test whether two strings are equal.
- Use the String.Compare and String.CompareTo methods to sort strings, not to check for equality.