Linq Group By Sum Multiple Columns

Ask Question How to do joins in LINQ on multiple fields in single join. MarketingLists select marketingList. DataSource = (from m in new Phones (). LINQ to SQL和Entity Framework都是一种包含LINQ功能的对象关系映射技术。 Group By Multiple Columns 8 answers ; LINQ to SQL语句之Select. SQL GROUP BY The SQL GROUP BY statement is used along with the SQL aggregate functions like SUM to provide means of grouping the result dataset by certain database table column(s). A protip by samudiogo about sql, linq, and c#. Pivot is a sql server operator that can be used to turn unique values from one column, into multiple columns in the output, there by effectively rotating a table. The query is used to group the invoice details into a single row per invoice, totaling the invoice amount and balance due. I've got a three column table, I would like to group by the first and second columns and sum the third. dataGridView1. Net; Group by Sum of column in DataTable using Linq in ASP. 语句描述:根据产品的―ID分组,查询产品数量大于10的ID和产品数量。这个示例在Group By子句后使用Where子句查找所有至少有10种产品的类别。 说明:在翻译成SQL语句时,在最外层嵌套了Where条件。 10. Group By Multiple Columns and Sum. 08 7 Sat 0 i need a query that converts DAY column to a header row and sort by SEQUENCE as follows: DAY Sun Mon Tue Wed Thu Fri Sat. This post details how to group and sum on multiple properties using lambda expressions. A derived table is a temporary table that is automatically materialized while the query is running, and automatically destroyed when the query is finished. The OVER and PARTITION BY functions are both functions used to portion a results set according to specified criteria. "How to select a field that is not in Group By clause in LINQ" PagaBruto = grouping. Output Note. I've blogged about this in detail here. StreamId into studentGroup select new { Stream = studentGroup. SupplierID } into g select new { g. There are tons of articles to display total in asp. One is to group by month,year,day and the other filter is to select if someone wants to group by product or company. I have attached a sample file for better understanding. Sum grouped row you can have multiple values for the DateField. group and sum. [Value]), First(dt1. 5 & Visual Studio 2008. Multiple Column Group count linq dataset. We illustrate this with two examples. End Class Column Attribute The Column attribute is used to designate a member of an entity class that represents a column in a database table. Thanks in advance!. Question How can I do GroupBy Multiple Columns in LINQ Something similar to this in SQL: SELECT * FROM GROUP BY , How can I convert this to LINQ: QuantityBreakdown ( MaterialID INT, ProductID INT, Quantity FLOAT ) INSERT INTO @QuantityBreakdown (MaterialID, ProductID, Quantity) SELECT MaterialID, ProductID, SUM. StreamId, s. select - Entity Framework - GROUP and SUM - Stack Overflow. We have seen the Join operator in the previous section. Group by UPC and sum these two columns. I’ve done it on MS Access and I am trying to convert to Linq or something to do on an Assign. Score, TotalCount = g. SELECT SUM(CASE WHEN assignment = '7' AND rank = '1' THEN 1 ELSE 0 END) AS firstshift. Group by multiple columns in Linq To SQL Wednesday, May 7, 2008 Today I was writing a Linq query in which I wanted to applying grouping to query based on more than 1 column and also apply filter on the group more like having clause. My source is a few columns of data. NET Forums / Data Access / ADO. Elements that are associated with matching key values are included in the same group. net - Group By Multiple Columns - Stack Overflow linq - Entity Framework T-Sql "having" Equivalent - Stack Overflow. c# - LINQ - Static columns transposition into aggr How php developers choose default constants values angularjs - update angular button after kinetics a php - Get the redirecting URL - WPF XBAP treeview unable to select child item - sql - comparing two strings with a different forma Connecting IOS Device to IBM DB2 using JDBC Bridge. Suppose we have a DB entity called Case and a class we've created called myCaseClass to represent the structure of that Case. It returns sum of numeric values in collection. The GroupJoin operator joins two sequences based on key and groups the result by matching key and then returns the collection of grouped result and key. Keys are compared by using a specified comparer and the elements of each group are projected by using a specified function. If you observe the above syntaxes, we are summing up the items in "Num" list using linq Sum() function. sql linq c#. Suppose we have a DB entity called Case and a class we've created called myCaseClass to represent the structure of that Case. Let me know if you have any luck with that. The use case was pretty typical - aggregate some pre-filtered set of invoices by the product sold, count how many sales were there for each product, order the data by total sales value and take. Sum (LINQ) Enumerable. Id where OrderLines. You can group by based on DepartMent column. LINQ allows queries to be executed that include grouping. 2, I needed to use some aggregations in my database queries. For example, SUM, MAX, MIN, COUNT, AVERAGE. Linq namespace. For instance you can use aggregate functions such as SUM and AVERAGE to calculate values. You typically use a GROUP BY clause in conjunction with an aggregate expression. net using c#, vb. OrderLines where Orders. Get Unique Selected Items From Multiple ASP. You can query the LINQ to SQL. I hope, this article will be helpful to understand how to write complex queries using LINQ or lambda. Grouping Rows. This is just something that can be done very simple in plain SQL. SupplierID } into g select new { g. C# Linq Group By on multiple columns. Linq with multiple table joins, ordering and grouping. I'm assuming of course by Lambda expression you mean a Linq statement (e. how to use group by clause in datatable Posted by Rajass22 under ASP. Name,sum(OrderLines. StreamId into studentGroup select new { Stream = studentGroup. dataGridView1. Since the first beta versions of LINQ we could hear comments that it is perfect for queries known at compile-time, however it is not possible to use it for building queries dynamically at runtime. How to Group By multiple columns in LINQ ? Hello, I was trying the sql query below Grouping by more than one columns, but it gives syntax errors !!! Can somebody help me convert this query to LINQ ? select rl. Product_Id,Products. Linq Group by and SUM of column? How to use Linq to group and SUM. If I have a set of the data of employee which has employee ID and if a group by the sql group by departmentid, anything else that is specific to the employee has to be aggregated somehow by using Sum, Min or Max , or may be aggregate. Is there a more elegant way?. NET Forums / Data Access / ADO. When doing a traditional join in SQL (or in LINQ) it doesn’t matter what entity you start with, but when using navigation properties it does matter. Linqer is a SQL to LINQ conversion tool. The table has 40+ columns consisting of invoice details. In this post, we'll (finally) cover one of. 0, so you can write queries like the LINQ query above in the next version of EF. To use column-based grouping, you must bind the data grid to a CollectionView, and this is then bound to the. Columnname) in the LINQ query we can easily order data of the source collection. select colums contains aggreagte function also. To make summary data in Access easier to read and understand, consider using a crosstab query. I'm aware there are a few 'sum column total' questions out there, however they don't deal with multiple tables and multiple column outputs. net using c#, vb. Just a simple listing. SQL query is able to populate the dataset from the database but not able to retrieve a particular value from the dataset. At run time a LINQ query that accessed a column with a null value. NE How to wrap text in a DataGridViewColumn. I'm assuming of course by Lambda expression you mean a Linq statement (e. LINQ is designed to fill the gap that exists between tradition. On the other hand adding every single column from the select clause to the group by will result in useless group clause that will return a group for each row in your table. In older Pandas releases (< 0. Any help would be greatly appreciated. NET Forums / Data Access / ADO. In our sample, I write code at Form_Load method to do so. This expression will be executed 3 (length of the list - 1) times: It is passed 2 and 4 for the sum and val parameters, and returns the sum: 6. I know it can be done e. I want to use SUM & GOUP BY in linq. This can be achieved by familiarizing on IGrouping which is a key/value pair interface. NET Elasticsearch LINQ Entity Framework C#. Using Group/By/Into will also give you the best possible performance for those complex queries. Net Using GroupBy, Count and Sum in LINQ Lambda Expressions (Finding information using VB, rather than C#, is also a little tricky. Joining Multiple Tables, Grouping And Evaluating Totals This is a continuation to the Join-Object blog post considering multiple joins and SQL style grouping and total evaluation. CategoryID, p. About DB 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. Linq query for multiple grouping and sum in vb. K1' in 'where clause' Below there are three variations of LINQ statements which all more or less result in same the exception. However, it’s not that easy in LINQ at the first look. Products group p by new { p. Once you can pivot data using the coalesce statement, it is now possible to run multiple SQL statements by pivoting the data and using a semicolon to separate the operations. 0 Group by Sum 효과 메소드 C#으로. This expression will be executed 3 (length of the list - 1) times: It is passed 2 and 4 for the sum and val parameters, and returns the sum: 6. Here I will explain how to calculate sum of datatable column in asp. SQL AVG Command AVG sql command is used to find out average value of a numeric field in a table. [Name]; I think this is a little upgrade from balareva package, but I can't get it to work =). DISTINCT will eliminate those rows where all the selected fields are identical. The examples in this topic demonstrate how to use the Average, Count, Max, Min, and Sum methods to query a DataSet and aggregate data using query expression syntax. I know how to do the sum part, but how do you group two different columns in a datatable? 在datatable中有三列:string、DateTime和decimal。. sum multiple columns linq (2). [Name]; I think this is a little upgrade from balareva package, but I can’t get it to work =). NHibernate's LINQ GroupBy capabilities Recently in the project that is using NHibernate 3. Querying and Searching XML Documents Using LINQ to XML - examines querying and filtering XML documents using the LINQ to XML API. IEnumerable. "How to select a field that is not in Group By clause in LINQ" PagaBruto = grouping. SQL Inner Join and Group by Clause is described as follows, SQL -select Products. What I try to think about when designing Linq queries is trying to only use aggregation functions that translate into SQL. [Date]) FROM dt1 GROUP BY dt1. I need to group the elements in the xml by Article_x0020_Tags. The GROUP BY clause groups records into summary rows. NET, Entity Framework, LINQ to SQL, NHibernate / Group by in DataTable using LINQ Group by in DataTable using LINQ [Answered] RSS 5 replies. I need to query the datatable using linq technique grouping and sum the amount and result to bind gridview. SQL Inner Join and Group by Clause is described as follows, SQL -select Products. I know how to do the sum part, but how do you group two different columns in a datatable? This is my code so far which doesn't work properly: var newSort = from row in objectTable. My partition is by CustomerNo – each “window” of a single customer’s orders will be treated separately from each other “window”…. It can be done by Select method or using selector as a parameter of the Average method. Average with Selector. [FirstName], Pro. This basically tells WPF to group by a specific property on the data objects, in this case the Sex property. Grouping Rows. This would at least mean that the where clause gets executed by LINQ to Entities, but the group clause, which is too complex for Entities to handle, gets done by LINQ to Objects. Group By multiple Columns in DataTable in C# using LINQ We might came across few scenarios where combination of columns makes Primary key in the DataTable. SupplierID } into g select new { g. The table has 40+ columns consisting of invoice details. NET Forums / Data Access / ADO. 求助linq to datatable group by sum的问题_百度知道 10. 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'm assuming of course by Lambda expression you mean a Linq statement (e. I initially starting using LINQ as it was easy to order the objects in a list without having to write a Comparer. The query is used to group the invoice details into a single row per invoice, totaling the invoice amount and balance due. In some cases, you will be required to use the SQL GROUP BY clause with the SQL MAX function. NET MVC, ASP. This can be achieved by familiarizing on IGrouping which is a key/value pair interface. c#,multithreading,file-search. SQL GROUP BY The SQL GROUP BY statement is used along with the SQL aggregate functions like SUM to provide means of grouping the result dataset by certain database table column(s). a decimal field in my datatable to be null How Group By And Sum Values In DataTable I want to sum of all TotalImages Column after Group BY but its showing me generic method to get linq result to datatable for select new with multiple selects. The WPF datagrid control supports grouping rows by their column values – making complicated tables easier to read – and this can be extended with expand and collapse functionality. Group by Multiple Columns using Anonymous Types in LINQ to SQL Posted on 30/06/2009 by Manoj I believe LINQ is a very nice advancement in creating database oriented applications as it allows us to separate application logic from the database. NET code, but use VB. Trying to expand the grouping based on what I've found so far has gotten me here, and I'm getting the feeling I'm going down the wrong path with it:. Group by Sum of column in DataTable using Linq in ASP. [Value]), First(dt1. This book explores what can be done with LINQ, shows how it works in an application, and addresses the emerging best practices. Suppose we have a DB entity called Case and a class we've created called myCaseClass to represent the structure of that Case. Results of DISTINCTROW queries are updateable. So I have a table with username, majorversion, time and buildname. GROUP BY typically also involves aggregates: COUNT, MAX, SUM, AVG, etc. 多列(Multiple Columns). Anticipated questions: What is your general approach here? Generate a really unique key from the given key, group the elements AND the key with that, and either reform new groups with Grouping or apply result to it, so that the original key type is still used. Multiple group by and Sum LINQ. It begins with basic single-column examples before illustrating how to use LINQ group by multiple columns. added), HowMany = Count. What's happening in this example? We have provided the lambda expression (sum, val) => sum + val to the Aggregate() method. In SQL Server you can only select columns that are part of the GROUP BY clause, or aggregate functions on any of the other columns. NET, Entity Framework, LINQ to SQL, NHibernate / Group by in DataTable using LINQ Group by in DataTable using LINQ [Answered] RSS 5 replies. Question: Tag: c#,arrays,string,linq,group-by I have a delimited file I am reading into a string array (file has no headers) and then trying to parse with a LINQ query. One is to group by month,year,day and the other filter is to select if someone wants to group by product or company. I had a different requirement - grouping by 2 columns should be done in a way so that the first column values would go top-to-bottom in the datatable and the second column values left-to-right as column names (kinda like crosstab). While multiple like-named columns are tolerated in SQL's workspace, they cannot be stored in SAS data sets. NET MVC 2, and Visual Studio 2010. NHibernate's LINQ GroupBy capabilities Recently in the project that is using NHibernate 3. var groupedData = from b in dataTable. It presents the general purpose query facilities offered by LINQ in the upcoming C# 3. 5's core features for both C# 3. This is how I recommend doing it. GROUP BY returns one records for each group. It begins with basic single-column examples before illustrating how to use LINQ group by multiple columns. Group By Clause Describes the From clause, which specifies a collection and a range variable for a query. Once you can pivot data using the coalesce statement, it is now possible to run multiple SQL statements by pivoting the data and using a semicolon to separate the operations. GroupColumn2, x. C# Linq Group By on multiple columns [duplicate] Ask Question Asked 8 years, 7 months ago. I am trying to figure out how to take some data from a datatable or class that could have 5 columns or could have 10 or 20 columns. itextsharp - Create a. This format is usual when binding data to a chart (each column represents chart series). CategoryID, p. 多列 (Multiple Columns): var categories = from p in db. public partial classLINQ: System. I will in this post mostly take advantage of "learning by example". How to create a multiple column Group By using LINQ to Entities VB. SQL SELECT with DISTINCT on multiple columns: Multiple fields may also be added with DISTINCT clause. The following code chunk sums all the TOTAL fields in a datatable where the field STATUS = NEW. NET[C#]LINQ按多列分组(Group By)并计算总和(Sum) SQL语句: SELECT * FROM GROUP BY , QuantityBreakdown ( MaterialID int, ProductID int, Quantity float) INSERT INTO @QuantityBreakdown (MaterialID, ProductID, Quantity) SELECT MaterialID, ProductID, SUM(Quantity) FROM @Transactions GROUP BY MaterialID, ProductID 在C#中,如何使用LINQ实现以上SQL. Pivot C# Array or DataTable: Convert a Column To a Row with LINQ. Have any of you worked on converting a SQL query with multiple joins and group by multiple columns. What's happening in this example? We have provided the lambda expression (sum, val) => sum + val to the Aggregate() method. Learn how to use LINQ in your applications with these code samples, covering the entire range of LINQ functionality and demonstrating LINQ with SQL, DataSets, and XML. Group Join Clause Describes the Group By clause, which groups the elements of a query result and can be used to apply aggregate functions to each group. NULLs are considered equivalent for grouping purposes. I have two filters. First, here is a basic Invoice class. SQL join tables with group by and order by Last update on September 19 2019 10:37:27 (UTC/GMT +8 hours) In this page, we are going to discuss the usage of GROUP BY and ORDER BY clause within a join. Into Group -or-Into = Group You can also include aggregate functions to apply to the group. I'm a big fan of LINQ, and one of my favorite extension methods is GroupBy. I have found that GroupBy is one of the most useful methods in LINQ and the more I use it the more useful I find it to be. GROUP BY returns one records for each group. It begins with basic single-column examples before illustrating how to use LINQ group by multiple columns. LINQ Tutorial. Calling functions in LINQ queries. Now, we will see the examples of using linq Sum() function in c# and vb. Linq join on multiple columns and multiple conditions You also can make join on multiple conditions, suppose you want data to be matched between more than one column, in that case you can write join on multiple columns and conditions. This tutorial starts with a general overview of LINQ, and then teaches you how to implement GROUP BY as you would in SQL. Hi: I've got a quick LINQ question regarding summing column values in a datatable. OrderQuantity)), or using a group by. How do i sum multiple columns in LINQ. I want to return multiple Sum columns LINQ SUM multiple remove grouping Linq using Sum() with NO GROUP BY. Products group prod by prod. Part 19 Group by multiple keys in linq - Duration: 10:38. LINQ Join Operators (Inner Join Left Join, Group Join, Cross Join) In LINQ, joining operators are used to join two or more lists / collections and get matched data from the collections based on specified expressions. Using Group/By/Into will also give you the best possible performance for those complex queries. I know it can be done e. First, here is a basic Invoice class. Example - Using SQL GROUP BY Clause. Using different SQL query. Using LINQ to group social networking. [Date]) FROM dt1 GROUP BY dt1. We have seen the Join operator in the previous section. How to group; How to group and count; How to group and sort a JS array; How to group arrays by multiple fields; How to Group By and Sum; How to group by array of objects; How to group complex JSON object by nested properties; How to group javascript object grouped by multiple attributes; How to hide HTML columns when exporting to Excel. 1), renaming the newly calculated columns was possible through nested dictionaries, or by passing a list of functions for a column. GroupColumn2, x. Suppose we have a DB entity called Case and a class we've created called myCaseClass to represent the structure of that Case. results in several columns containing NULL values including the. Each row is a separate line item within an invoice, which can consist of 1 to n rows. StreamId, s. With GroupJoin, from the System. Querying and Searching XML Documents Using LINQ to XML - examines querying and filtering XML documents using the LINQ to XML API. The examples in this topic demonstrate how to use the Average, Count, Max, Min, and Sum methods to query a DataSet and aggregate data using query expression syntax. This sample shows different uses of Grouping Operators LINQ - Grouping Operators in C# for Visual Studio 2010 This site uses cookies for analytics, personalized content and ads. Orderby(x=>x. Net language. I have records in a collection & want to use the below query to execute on the. How Group by works with C# Linq. In such cases we may need to group by multiple columns in the DataTable and create unique records in the table. Linqer is a SQL to LINQ conversion tool. You can use LINQ to write queries that perform grouping of data using group by or ordering of data using orderby clause. kudvenkat 39,768 views. I want to return multiple Sum columns LINQ SUM multiple remove grouping Linq using Sum() with NO GROUP BY. Visual Studio Languages ,. Using COUNT and GROUP BY with multiple tables, including derived tables? counts when joining multiple one-to-many tables. A GROUP BY clause, part of a SelectExpression, groups a result into subsets that have matching values for one or more columns. NET, Entity Framework, LINQ to SQL, NHibernate / Group by in DataTable using LINQ Group by in DataTable using LINQ [Answered] RSS 5 replies. The GROUP BY statement is often used with aggregate functions (COUNT, MAX, MIN, SUM, AVG) to group the result-set by one or more columns. ) Using a Console Application, let's set up the data using a simple Staff class and List(Of Staff). NET LINQ to dataset. This article explains how to calculate Sum (Total) of DataTable Columns using the following two methods. UnitAmount). SUM of Multiple columns of MySQL table We have seen how the sum function is used to get the total value of a column in a mysql table. Now that we have our single column selected from our GroupBy object, we can apply the appropriate aggregation methods to it. Learn how to use LINQ in your applications with these code samples, covering the entire range of LINQ functionality and demonstrating LINQ with SQL, DataSets, and XML. I am trying to figure out how to take some data from a datatable or class that could have 5 columns or could have 10 or 20 columns. This allows not only to use LINQ-specific query language in a standard VB. OrderQuantity)), or using a group by. 08 7 Sat 0 i need a query that converts DAY column to a header row and sort by SEQUENCE as follows: DAY Sun Mon Tue Wed Thu Fri Sat. Amount) } Select all Open in new window. Quantity) as OrderQuantity from OrderLines where OrderLines. Key, GroupScore = studentGroup. This basically tells WPF to group by a specific property on the data objects, in this case the Sex property. Input XML: Checking Interest Checking Account Dollar 10000000. Linq is implementing grouping quite the same way. A simple SQL Group by for Linq and Lambda would be as follows, SQL - select SUM(OrderLines. kudvenkat 634,651 views. I'm a big fan of LINQ, and one of my favorite extension methods is GroupBy. I had a different requirement - grouping by 2 columns should be done in a way so that the first column values would go top-to-bottom in the datatable and the second column values left-to-right as column names (kinda like crosstab). One of the extension methods in the System. Find Duplicates using LINQ So I remove the duplicates by grouping by the "Code" attribute, allowing only groups with one element. var groupedData = from b in dataTable. Optimizing Sum, Count, Min, Max and Average with LINQ. This has been answered already, but the other answers will still do multiple iterations over the collection (multiple calls to Sum) or create lots of intermediate objects/Tuples which may be fine, but if it isn't, then you can create an extension method (or multiple) that does it the old-fashioned way but fits well in a LINQ expression. Whenever you hear the word projection while writing LINQ or lambda queries, it is nothing but your Select statement. NET Framework > Visual C#. This is the only operator that falls in the category of grouping operator. This is how I recommend doing it. Group by Multiple Columns using Anonymous Types in LINQ to SQL Posted on 30/06/2009 by Manoj I believe LINQ is a very nice advancement in creating database oriented applications as it allows us to separate application logic from the database. AccountNumber) SumAmount = g. Conclusion. StreamId select new { StreamId = g. GROUP BY typically also involves aggregates: COUNT, MAX, SUM, AVG, etc. NET ListBox and Merge them using LINQ - I recently did a short article on Get Selected Items From Multiple ASP. LINQ in Action is a fast-paced, comprehensive tutorial for professional developers. Now there is a f. C# / C Sharp Forums on Bytes. Sample LINQ Queries. NET code in a LINQ query. I have three columns in a datatable: string, DateTime, and decimal. Quantity) as OrderQuantity from OrderLines where OrderLines. NET, which offers strong typing and full Object-Oriented approach; LINQ introduces an easy learn approach for querying and modifying data and can support querying various types of data sources including relational data, XML and in-memory data structures. I've done it on MS Access and I am trying to convert to Linq or something to do on an Assign. Okay, everyone knows by now how simple LINQ queries with a where and select (and orderby, and Take and Skip and Sum, etc) are translated from a query comprehension into an equivalent expression. 3, “MySQL Handling of GROUP BY”. So if query results are feeding a CREATE TABLE or CREATE VIEW statement, only the first one will be saved, and warnings will be issued for subsequent columns with duplicative names. In SQL Server you can only select columns that are part of the GROUP BY clause, or aggregate functions on any of the other columns. C# GroupBy Method: LINQ If each group contains multiple elements as is typical with GroupBy, you could use a List as the value of the Dictionary instance. Net Framework Ver 4. var groupedData = from b in dataTable. DataSource = (from m in new Phones (). Part 3 Why and when should we use an abstract class - Duration: 20:29. LINQ Tutorial. net tutorial we will learn how to display sum of columns total in gridview footer using asp. Group By using Multiple Columns in SQL - Duration: 6:25. Products group p by new { p. select colums contains aggreagte function also. The following example uses the Pivot() function to group Employees by Department and Function and aggregates the Salary using a SUM. Let's understand the power of PIVOT operator with an example Create Table tblProductSales ( SalesAgent nvarchar (50), SalesCountry nvarchar (50), SalesAmount int). I have something like this now. Sum() - however that doesn't work if the column name is not known at complile time. NET, which offers strong typing and full Object-Oriented approach; LINQ introduces an easy learn approach for querying and modifying data and can support querying various types of data sources including relational data, XML and in-memory data structures. If we group by using the SQL clause we get the flat record set. Using LINQ. Amount into g select new { InstNumber = (item => item. 多列(Multiple Columns) var categories = from p in db. 4 September 2014. Count Examples. In this example, I am grouping by Age and Sex to find the count of people who have the same age and sex. C# - LINQ - group/sum multiple columns - Stack Overflow. Products group p by new { p. In older Pandas releases (< 0. Linq namespace. How Group by works with C# Linq. Note that there is optimization. StreamId select new { StreamId = g. Each row is a separate line item within an invoice, which can consist of 1 to n rows. The shortest query string does not necessarily yield best performance. net using c#, vb.