How does linq group by work

Elements in a grouping are yielded in the order they appear in source". Won't this mean First will always return A, E? CodeCaster You're right,. NET's hash dictionaries do have predictable ordering. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog.

Does ES6 make JavaScript frameworks obsolete? Podcast Do polyglots have an edge when it comes to mastering programming Featured on Meta. Now live: A fully responsive profile. Example: GroupBy in Query syntax C. Try it. Example: GroupBy clause in VB. StudentName Next Next. Example: GroupBy in method syntax C. Example: GroupBy in method syntax VB. GroupBy Function s s. The solution is to do this 2nd attempt in my question :. The reason intellisense didn't show Include after the query was because I needed the following using:.

It throws an exception if there is more than one such instance. ID is equal to ID. It basically separates the left-hand side of the lambda expression from the right-hand side. The left-hand side are the input variables. It's equivalent to the parameter list in an explicitly-defined method. That is s in the lambda expression plays the role of s below:. It's just that you don't have to declare the type of s as the compiler will infer it.

The nice thing is the compiler just automatically spits this out for you when you use a lambda expression. Asked 3 Months ago Answers: 5 Viewed 15 times. However, you are free to create your own keys which contain several values - these are called composite keys. A usage example could be if we wanted to group our users based on both their home country and their age, like this:. Notice the syntax we use in the GroupBy method - instead of supplying a single property, we create a new anonymous object, which contains the HomeCountry and the Age properties.

LINQ will now create groups based on these two properties and attach the anonymous object to the Key property of the group.

We are free to use both properties when we iterate over the groups, as you can see. It really allows you to use your data in new ways, with very little code. Previously this would either be very cumbersome or require a relational database, but with LINQ, you can use whatever data source you'd like and still get the same, easy-to-use functionality. C Tutorial.