The Join operator joins two sequences (collections) based on a key and returns a resulted sequence. Joins. Outer Key selector (common key in the outer data source) Inner Key selector (Common key in the inner data source) Result selector (project the data into a result set) Let us understand the Linq Inner Join with some examples. Entity Framework LINQ joining 5 tables on multiple columns … linq join on multiple columns. Group By Multiple Column In LINQ in C# - Entity Framework on new { CutomerId = order.CustomerId // column 2 } equals new { CutomerId = cust.CustomerId // condition 2 } Linq Join On Multiple Columns - XpCourse Multiple LINQ Join conditions with differing comparison operators Now we group multiple preperties of objects for example. Join by using composite keys (LINQ in C#) | Microsoft Docs Linq Inner Join in C#