by (C# Reference)


Updated: July 20, 2015

For the latest documentation on Visual Studio 2017 RC, see Visual Studio 2017 RC Documentation.

The by contextual keyword is used in the group clause in a query expression to specify how the returned items should be grouped. For more information, see group clause.

The following example shows the use of the by contextual keyword in a group clause to specify that the students should be grouped according to the first letter of the last name of each student.

            var query = from student in students
                        group student by student.LastName[0];

LINQ Query Expressions