Linq group by select multiple columns

By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. Github issue :. Though this question is asking about group by class properties, if you want to group by multiple columns against a ADO object like a DataTableyou have to assign your "new" items to variables:.

A thing to note is that you need to send in an object for Lambda expressions and can't use an instance for a class. If you wan't to name the key properties and then retreive them you can do it like this instead. This will GroupBy correctly and give you the key properties. Learn more. Asked 10 years, 11 months ago. Active 3 months ago. Viewed k times. ArunPratap 3, 6 6 gold badges 19 19 silver badges 36 36 bronze badges. Sreedhar Sreedhar 24k 30 30 gold badges 97 97 silver badges bronze badges.

Linq GroupBy and Sum over two fields

Active Oldest Votes. Use an anonymous type. Column1, x. If you're new to grouping with anonymous types the use of the 'new' keyword in this example does the magic. I thought in this case the new objects would by compared by reference, so no match - no groupping.

HoGo anonymous typed objects implement their own Equals and GetHashCode methods which is used when grouping the objects. A bit tough to visualize the output data structure when you're new to Linq. Does this create a grouping where the anonymous type is used as the key? Procedural sample. Pranay Rana k 33 33 gold badges silver badges bronze badges. Mo0gles Mo0gles 8, 1 1 gold badge 17 17 silver badges 14 14 bronze badges. What type is the object returned?

This code is not working for me: "Invalid anonymous type declarator.In LINQ, grouping operators pick the elements of the sequence or collection which contains common attributes and serve them in a group. Or in other words, we can say that the grouping operator returns the group of elements based on the given key. For example, a sequence contains 6 elements, i. Now we want a group which contains all the Abc present in that sequence.

So Abc is the key through which we create another group that contains 3 Abc. As shown in the below image:. It is used to return the group of elements which share the common attributes or key from the given sequence or collection.

If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute. See your article appearing on the GeeksforGeeks main page and help other Geeks. Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below. Writing code in comment? Please use ide. NET 3-Tier Architecture? How to Execute C Program on cmd command-line? As shown in the below image: The Standard Query Operator contains 2 different types of grouping operators:.

Key. Check out this Author's contributed articles. Load Comments. Linq; using System.I believe that multiple column Group By on the raw detail data is one of the most important query for reports and user output analysis, because only in the raw detail data you can sum, count and calculate transactional information based on a certain header information.

This problem should be simple, because in Microsoft Access it is pretty darn simple using Queries, but unfortunately I could not find any simple LINQ to Entities code for this problem in the Internet. As you can see in the above example you can have multiple columns in the Group By section, which is very important.

To test whether our example is correct I open a LinqPad software, which you can download for free here. Any chance you can send me a code snippet how to use the linq groupby as a result for a computedfield in my table? Use a parameter RIA Service. The computed field is sent through a parameter.

Below is an example group by with parameter. By the way, you need to create first a default query before you could create a parameter query. TrnInventories Where i. MstArticleUnits Where u.

Min Function q q. InventoryDateTime. Max Function q q. Where Function q q. Value And q. Sum Function q q. QuantityOut. QuantityIn - q.

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How to group by linq dynamically based on column selection Ask Question. Asked today. Active today. Viewed 21 times.

LambdaAction t. ToListAsync ; switch request. Cherry R. Cherry R Cherry R 43 5 5 bronze badges. What is the exact error message? All the working ones have FirstOrDefault. Why does the broken one lack that? Active Oldest Votes. Sign up or log in Sign up using Google.

linq group by select multiple columns

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linq group by select multiple columns

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How can I select multiple columns? Like I want to select res. ID aswell. And how can I receive those? IQueryable will not work I think. And this is called Linq to SQL - right? As far as syntax is concerned, I personally far prefer method chaining.

The method chaining equivalent would be If you want the entire object, then you just have to omit the call to Selecti. Learn more. Linq Syntax - Selecting multiple columns Ask Question. Asked 8 years, 9 months ago. Active 2 years, 8 months ago. Viewed k times. Gilad Green Riz Riz 5, 15 15 gold badges 54 54 silver badges 77 77 bronze badges.

LinqToSql and entity framework are different. See stackoverflow. Active Oldest Votes. As the other answers have indicated, you need to use an anonymous type.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. Code Review Stack Exchange is a question and answer site for peer programmer code reviews. It only takes a minute to sign up.

linq group by select multiple columns

From what you gave us, there's nothing you can do to optimize your query except changing the way your data is stored. There's something wrong in the implementation. This could be extracted in a method but beforehand, we need to create a small data type for your anonymous type because methods cannot return anonymous types.

Notice the???

Selecting multiple columns in group by and aggregate functions in LINQ

In your next question, please add more context! The naming is pretty terrible. Also, variable shouldn't be PascalCased, but camelCased. Lastly, try to use var only when it's possible to guess the type used by reading the code. Edit : I don't think this code even works.

Because you use it in the Sum function, which takes an intbut you also check for nullwhich isn't a possible value for int. What does that mean?? First and most obvious issue is usage of ToListit's not required and you force creation of multiple and possibly big lists moreover you're repeating almost same code again and again. Step by step:. Also you don't need. ToListdrop it. If you will execute such code inside a loop you may consider to move this outside the loop to be sure more context is needed.

Now let's make a reusable function and also avoid to create multiple anonymous types, it's a micro optimization but it also simplifies our code :. Now your code can be greatly simplified I assumed you cannot change database columns otherwise everything can be even simpler, see last section of this answer. I also used generics because type of your columns is unknown.

If you have just one row then all code will be greatly reduced. Note that you can consume result as-is an enumeration or materialize a list don't forget this if data comes from DB and connection will be disposed, LINQ execution is deferred.

I do not know if you can change your database schema and I do not know exact layout of your data then this section may not apply in your case. Sign up to join this community.

Group by in sql server - Part 11

The best answers are voted up and rise to the top. Home Questions Tags Users Unanswered. Group by and sum query on multiple columns Ask Question. Asked 4 years, 4 months ago. Active 4 years, 4 months ago. Viewed 84k times. Arijit Mukherjee Arijit Mukherjee 1 1 gold badge 1 1 silver badge 5 5 bronze badges.

You're jumping through hoops because it's not been properly normalized. Active Oldest Votes. Though, you could change this code to be a little less repetitive.This caused me a few hurdles. The acronym is pretty cool, though, and is easy to say, which goes in its favor.

The example above uses to LINQ to query from a database, which is a very common use case. However, you could also query other data sources, like an XML document or a. NET collection. There are two different types of syntax that you can use to query with LINQ: query syntax and method syntax.

Query syntax looks similar to SQL, while method syntax involves making method calls with lambdas as parameters much of the time. You can see that it looks very similar to SQL syntax, with a few differences.

You can also easily see the C comparison operator.

How to create a multiple column Group By using LINQ to Entities VB.NET?

Which syntax you decide to use comes mostly down to personal preference, although some features of LINQ can only be expressed in method syntax. There are also some types of queries that are simply easier to write in one version vs. We also want to keep track of who submitted the recipe, so we have an Author column. Just keep in mind that you could take any of the following examples and use the foreign keys to group by instead of a text field. What I slowly forgot, over time, was the first part of the definition.

Keep this in mind as we move forward. In LINQ, you need to create these groups explicitly. The line group r by r. We could have also created a strongly-typed object, like a view model, and created a new instance of that. Finally, we get to our original question. In order to group by multiple columns, the structure of our queries is basically the same as before. However, instead of grouping by one property, we need to create a new anonymous object and group by that object.

Also notice that we had to change the OrderBy parameter from g. Key to g. Since our grouping now contains Author and Category, we need to tell the query which property to order by. You can make quick changes to your code and get instant feedback on the results of that LINQ query.


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