C# – LINQ GroupBy Examples

GroupBy is a LINQ functionality which allows to group items from a collection based on a given key. It’s an equivalent to SQL’s GROUP BY clause. In this article we’ll show various examples of usage, starting from the simplest grouping by one key, through grouping by multiple keys, custom result selector and all of that in two variants: Lambda and Query expression.

Continue reading C# – LINQ GroupBy Examples

C# – LINQ FirstOrDefault Examples

FirstOrDefault is a LINQ functionality to return first element of the collection or default value if requested item does not exist. In case of collection of reference type objects the default is null, whilst in case of value types the default depends on the particular type (e.g. for int it is 0).

FirstOrDefault is overloaded method which can be used with either zero or one parameter. The first option just returns first element and the second one allows to define condition which needs to be met. Continue reading C# – LINQ FirstOrDefault Examples