LINQ
- Simple Func delegate example with LINQ in .NET C#
- Filter an array of integers with LINQ C# using a lambda expression
- Convert array of strings to integers with C# LINQ
- Projection in LINQ C# with the Select operator
- Projection in LINQ C# with the SelectMany operator
- Performing joins across two sequences with the LINQ Join operator
- Joining unique values from two sequences with the LINQ Union operator
- Finding the set difference between two sequences using the LINQ Except operator
- Joining two collections using the C# Concat LINQ operator
- Selecting a subset of elements in LINQ C# with the Take operator
- Creating a grouped join on two sequences using the LINQ GroupJoin operator
- Reversing a sequence using the Reverse operator in .NET LINQ
- Determine if a sequence contains a certain element with LINQ C#
- Determine if all elements fulfil a condition in a sequence with LINQ C#
- Determine if two sequences are equal with LINQ C#
- Joining common values from two sequences using the LINQ Intersect operator
- Grouping elements in LINQ .NET using GroupBy
- Converting a sequence of objects into a Lookup with LINQ C#
- Grouping elements in LINQ .NET using GroupBy and an EqualityComparer
- Finding unique values using the LINQ Distinct operator
- Converting a sequence to a dictionary using the ToDictionary LINQ operator
- Determine the presence of an element in a sequence with LINQ C#
- Convert a sequence of objects to a sequence of specific type in LINQ .NET
- Getting the last element from a sequence with LINQ C#
- Retrieving an element from a sequence with an index in LINQ C#
- Getting the first element from a sequence in LINQ C#
- Finding the minimum value in a sequence with LINQ C#
- Selecting a subset of elements in LINQ C# with the TakeWhile operator
- Ordering a .NET data sequence with various LINQ operators
- Selecting a subset of elements in LINQ C# with the SkipWhile operator
- Finding the average value in a sequence with LINQ C#
- Finding the factorial for a number using Aggregate in LINQ C#
- Finding the maximum value in a sequence with LINQ C#
- Breaking up a collection into smaller fixed size collections with C# .NET
- Randomly rearrange a string in .NET C#
- Concatenate two IEnumerable sequences in C# .NET
- Creating an empty sequence using the Empty operator in LINQ
- An example of grouping and joining collections in .NET: calculate total scores by student and subject
- An overview of grouping collections with LINQ in .NET
- Flatten sequences with the C# LINQ SelectMany operator
- Using the let keyword in .NET LINQ to store variables within a statement
LINQ to XML
Exercises in .NET with Andras Nemes 
Hi Andras
Nice articles, would appreciate if you get a chance to answer a question related to LINQ.
http://stackoverflow.com/questions/39910906/linq-merge-into-single-record-with-unique-description