Linq distinct by field. Name,p. ToList(); If you want to get distinct objects of a custom type, then you need to implement IEquatable generic interface and provide your own GetHashCode and Equals methods for the type. But I want to sort it on a different field. Distinct on Multiple Columns Entity Framework LINQ Asked 13 years, 6 months ago Modified 4 years, 5 months ago Viewed 37k times Hi I'm using linq to entity in my application. ID, p. In the simple case, it can be used with no parame 5 By "distinct by multiple columns" what you really mean is a group by. If you want to avoid this anonymous type here is the simple trick. Explore multiple C# LINQ methods to achieve distinct items based on specific properties, including GroupBy, DistinctBy, and custom comparers. You therefore have to map a . You can achieve that by using the Distinct extension method : How can I do this SQL query with Entity Framework? SELECT DISTINCT NAME FROM TestAddresses Jun 5, 2023, 6:42 PM Hi @Mansour_Dalir , You could refer to the following code. By default, Distinct () compares all properties of the objects in the collection to determine if they are distinct. I know that Distinct was made for the job but I linq distinct field Asked 15 years, 10 months ago Modified 15 years, 10 months ago Viewed 2k times. I want Red Brown Yellow Green Orange var uniqueColors = from dbo in da Is this LINQ-to-Objects or LINQ-to-SQL? If just objects, you're probably out of luck. Distinct. IQueryable 1[DAL. Distinct in LINQ. Returns distinct elements from a sequence. Wha LINQ query to return distinct field values from list of objects Asked 14 years, 8 months ago Modified 4 years, 1 month ago Viewed 343k times So, you definitely should have distinct anonymous objects, when iterating on distinct collection. Let’s look at the tool tips for the Distinct keyword: This keyword, Distinct, returns an IEnumerable. MyDOClass] Distinct[MyDOClass](System. I can get the distinct values and fill my List, bu I'm new to Linq and I'm wondering how you would write this in Linq query syntax in stead of Linq method syntax. RequiresDynamicCode ("Enumerating collections as IQueryable can require creating new generic types or methods, which requires creating code at runtime. LINQ to Objects doesn't provide anything to do "distinct by a projection" neatly. Learn more. LINQ Distinct is a powerful feature that enables developers to remove duplicate elements from a collection efficiently. I need to get distinct records based on one column value "Name" So I have a table similar like you can see below: (User) ID Name Country DateCreated I Extracting unique values from a sequence of objects in LINQ is very easy using the Distinct operator. I am trying to get distinct rows based on multiple columns (attribute1_name, attribute2_name) and get datarows from datatable using Linq-to-Dataset. I've found two ways to go about it; either use GroupBy or Distinct. See MSDN for details. Selecting the key fields into an anonymous type, then using Enumerable. Field(Of String)("B")) Select the value of column B. In this tutorial, you will learn how to use the LINQ DistinctBy() method to return distinct elements from a sequence according to a specified key selector function. Returns distinct elements from a sequence by using the default equality comparer to compare values. Value = '10'; MyObject b = new Object(); b. MyDOClass])' method, and this method cannot be translated into a store expression. Whether you're working with a large dataset or managing complex data structures, utilizing LINQ Distinct can significantly streamline your data analysis process. net vb. Generic. 2 I have an objectset and want to perform a DISTINCT on the collection. If you want to only get distinct groupings for a subset of the columns, then use a group by in your clause, specifying the columns to group by. I am playing with LINQ to learn about it, but I can't figure out how to use Distinct when I do not have a simple list (a simple list of integers is pretty easy to do, this is not the question). Linq namespace. It returns a new sequence containing only the unique or distinct elements from the source. To select distinct objects based on multiple properties, pass in an anonymous type with the properties you want. To get started using the Distinct keyword, we must first use the System. e. It comes in two versions: one with a default equality comparer and another which lets you provide a custom comparer. I want to use the properties so projecting really isn't an option. AsEnumerable() converts the DataTable into an enumerable collection. When you ask for distinct, it means that you are getting ALL the distinct rows, or, a group by using all the columns in the table. Of the 10 properties, I only want the DISTINCT applied to two of the fields (DistrictId and ContactId). I have a datatable with a column that has some duplicate values, I want to add those values to a listbox but without duplicates I tried the following Dim a = From row In table. And result does not depend on how many fields you use for your anonymous type. AsEnumerable. Jan 14, 2013 · One of the most popular suggestions have been the Distinct method taking a lambda expression as a parameter as @Servy has pointed out. For example, this is selecting distinct movies per director per year: This outputs the following: Note: If you’re using DistinctBy() you also pass in an anonymous type for selecting by multiple properties, like this DistinctBy(t => new { Learn how to apply LINQ’s Distinct () method to filter unique items based on a specific property in C# with practical examples. I want results like this attribute1_name The LINQ distinct() function is used in C# to remove all the duplicate elements from a list and return the unique elements present in that particular list. The simplest option is to use GroupBy () since it doesn't require additional code. Select(Function(row) row. MyDOClass], System. Select(m => m. The chief architect of C#, Anders Hejlsberg has suggested the solution here. Name I am trying to use LINQ (to EF) to get a DISTINCT list and then sort it. IQueryable 1 [DAL. IQueryable<TSource> source); static member C# Linq example on how to use the Distinct method to find unique items in an array or list. This article will discuss the basics of using the Distinct() function in LINQ and obtaining a distinct list based on one or more properties in C#. How can I get the distinct values of first integer property from my list? I am wondering how can I achieve this? I want to get only distinct names from a collection of objects MyObject a = new Object(); a. So, let's say table A has fields x, y, z, 1, 2, 3 where x Learn how to use the distinctby multiple fields method in Cto efficiently remove duplicate rows from a data source. Distinct(). Distinct () is faster but more complex, and DistinctBy () is the most efficient, but requires . Linq to sql has no support for Count (Distinct ). I am trying to figure out if I can use LINQ to provide me with the distinct values of some data I have in a DataTable (FirstName, LastName, QTY). Right, so I have an enumerable and wish to get distinct values from it. I guess this is possible and much simpler than the way in . However, you can also specify a custom equality comparer to compare only specific fields of the objects. NET method in code onto a Sql server function (thus Count (distinct. Distinct() returns an indistinct value. Phone) How would I return the Distinct records based only on the ID? Learn what is C# Linq Distinct() explained with suitable examples. A typical example is the OrderBy method. But instead of selecting the anonymous type i'm joining it with the original collection of employees (note the select e at the end). Example: C# Linq example on how to use the Distinct method to find unique items in an array or list. The objects returned have about 10 properties each. Here's an example of how to use Distinct () with multiple fields: Feb 10, 2025 · There are multiple ways to select distinct objects based on a property in LINQ. NET 9: CountBy and Index I've been trying to get a Linq query to return distinct values from a collection. CodeAnalysis. See examples with value types, string values, complex data types and anonymous types. I have a list like this: Red Red Brown Yellow Green Green Brown Red Orange I am trying to do a SELECT UNIQUE with LINQ, i. You can use the Distinct method for a list of integers and for a list of objects. This LINQ statement will pull all of the records for Active users within a certain time period, and then s How to LINQ Distinct by Multiple Fields without anonymous types Asked 14 years, 8 months ago Modified 12 years ago Viewed 43k times One benefit to this approach (instead of group by + first) is you can return a yieldable enumerable in case you have later criteria that don't force you to loop through the entire collection Further Reading: linq query to return distinct field values from a list of objects If you've ever wanted to filter a collection for a distinct result you probably know about the extension-method . net linq linq-to-objects distinct edited Jul 2, 2011 at 13:04 asked Jul 2, 2011 at 9:06 OrElse You can only perform a Distinct on all the fields you select, not just on one field (which values would you take for other fields ?). You could group by the name and then take the first element in each group, but that's pretty ugly. )) and use that. NET 6 or an external library. 202 This question already has answers here: LINQ's Distinct () on a particular property (23 answers) In this tutorial, you'll learn how to use the LINQ Distinct() method to return distinct elements of a sequence. net 3. net 2. IQueryable<TSource> Distinct<TSource> (this System. I am working on getting the results of this sql query in LINQ SELECT DISTINCT(Type) FROM Product WHERE categoryID = @catID this is my repository query: public IQueryable<ProdInfo> GetPr The obvious problem is that the distinct-set doesn't contain all the data (say you have three fields but only want to distinct on two fields missing out on the value for the last field, but, then again, DISTINCT in t-sql works the same way). Peeking Into LINQ DistinctBy Source Code # csharp # dotnet # beginners # tutorial Getting Started with LINQ (7 Part Series) 1 A Quick Guide to LINQ With Examples 2 Three Common LINQ Mistakes and How To Fix Them 3 more parts 6 Three LINQ Set Methods: Intersect, Union, and Except 7 Two New LINQ Methods in . . All the examples I found sort the result based on the DISTINCT value. Explore how does it remove the duplicate elements from a sequence and returns the distinct elements. . It can be useful on simple data structures containing easily comparable objects, like I collection of strings or ints, but for more complex scenarios you need to pass in a IEqualityComparer. dtParent. I would like to get rid of all of the items in that list where the Guid and DateTime a Here's an example of how to use LINQ's Distinct() method to filter unique values based on a particular property. Linq, there's, of course, an extension method called Distinct. Without the selector parameter, even a st LINQ to Entities does not recognize the method 'System. Diagnostics. ")] public static System. Syntax I have a requirement to get the list of distinct values for specific properties of a collection of entities. How do I do this? List<int> ListOfIDs = myList. I have a list<message> that contains properties of type Guid and DateTime (as well as other properties). And here is the implementation of EqualityComparer: 17 You can select multiple fields using linq Select as shown above in various examples this will return as an Anonymous Type. Select distinct using linq [duplicate] Asked 12 years, 4 months ago Modified 8 years, 6 months ago Viewed 849k times 241 Are you trying to be distinct by more than one field? If so, just use an anonymous type and the Distinct operator and it should be okay: Select All distinct values in a column using LINQ Asked 12 years, 3 months ago Modified 3 years, 5 months ago Viewed 186k times Returns distinct elements from a sequence according to a specified key selector function. id). This method is often used to improve performance when working with large datasets. Linq. Collections. Name = 'One'; a. LINQ-code (hence the Dump): Since the inception of LINQ, methods suffixed with 'By' have played an important role in simplifying LINQ operations by introducing an additional 'selector' parameter. Given: var s = (from p in operatorList select p. This may not work when AOT compiling. IEqualityComparer`1 [DAL. [System. However, if L2S, then it may work, as the DISTINCT would be passed onto the SQL statement. ToArray() converts the result to an array of strings. 5 lambda or linq to get a list of MyClass by distinct value1. Using System. 0 to cache a list like this: I have a list of objects with three integer properties. I would like to use . I'm writing a Function that pulls Records from a DataBase using LINQ to get an IQueryable. How to select distinct based on combination of two fields with LINQ? Asked 12 years, 10 months ago Modified 2 years, 7 months ago Viewed 8k times What is the LINQ Distinct () Method? The Distinct () method in LINQ (Language Integrated Query) provides an easy way to remove duplicates from a sequence in C# based on an equality comparison. Learn how to use the LINQ Distinct Method to remove duplicate elements from a collection based on default or custom equality comparer. 4hljha, umcw, 809kt, 2w21, 9laat, ng1v, 66mqe2, vw6a9, moc0u, aq6gz,