DataTableExtensions.AsEnumerable(DataTable) Method

Reference

Definition

Namespace:: System.Data

Assembly:: System.Data.Common.dll

Assembly:: System.Data.DataSetExtensions.dll

Assembly:: netstandard.dll

Package:: System.Data.DataSetExtensions v4.5.0

Source:: DataTableExtensions.cs

Source:: DataTableExtensions.cs

Source:: DataTableExtensions.cs

Important

Some information relates to prerelease product that may be substantially modified before it’s released. Microsoft makes no warranties, express or implied, with respect to the information provided here.

Returns an IEnumerable<T> object, where the generic parameter T is DataRow. This object can be used in a LINQ expression or method query.

public:
[System::Runtime::CompilerServices::Extension]
 static System::Data::EnumerableRowCollection<System::Data::DataRow ^> ^ AsEnumerable(System::Data::DataTable ^ source);

public static System.Data.EnumerableRowCollection<System.Data.DataRow> AsEnumerable (this System.Data.DataTable source);

static member AsEnumerable : System.Data.DataTable -> System.Data.EnumerableRowCollection<System.Data.DataRow>

<Extension()>
Public Function AsEnumerable (source As DataTable) As EnumerableRowCollection(Of DataRow)

Parameters

source: DataTable

The source DataTable to make enumerable.

Returns

EnumerableRowCollection<DataRow>

An IEnumerable<T> object, where the generic parameter T is DataRow.

Exceptions

ArgumentNullException

The source DataTable is null.

Examples

In the following sample, the DisplayProducts method receives a DataTable that contains a DataColumn named ProductName, extracts the ProductName values and then prints the values.

using System;
using System.Data;

class Program {
   public void DisplayProducts(DataTable table) {
      var productNames = from products in table.AsEnumerable() select products.Field<string>("ProductName");
      Console.WriteLine("Product Names: ");
      foreach (string productName in productNames) {
         Console.WriteLine(productName);
      }
   }

   static void Main(string[] args) {
      DataTable table = new DataTable();
      table.Columns.Add("ID");
      table.Columns.Add("ProductName");

      table.Rows.Add("1", "Chai");
      table.Rows.Add("2", "Queso Cabrales");
      table.Rows.Add("3", "Tofu");

      Program inst = new Program();
      inst.DisplayProducts(table);
   }
}

Imports System.Console

Module Module1
   Public Sub DisplayProducts(ByVal table As DataTable)
      Dim productNames = From products In table.AsEnumerable() Select products("ProductName")
      WriteLine("Product Names: ")
      For Each productName In productNames
         WriteLine(productName)
       Next
   End Sub

   Sub Main()
      Dim table As DataTable = New DataTable()
      table.Columns.Add("ID")
      table.Columns.Add("ProductName")

      table.Rows.Add("1", "Chai")
      table.Rows.Add("2", "Queso Cabrales")
      table.Rows.Add("3", "Tofu")

      DisplayProducts(table)
   End Sub
End Module

Remarks

Language-Integrated Query (LINQ) queries work on data sources that implement the IEnumerable<T> interface or the IQueryable interface. The DataTable class does not implement either interface, so you must call the AsEnumerable method to use the DataTable as a source in the From clause of a LINQ query. You can also obtain custom, domain-specific operators, such as CopyToDataTable, by returning an IEnumerable<T> object.

The enumerable object returned by the AsEnumerable method is permanently bound to the DataTable that produced it. Multiple calls to the AsEnumerable method will return multiple, independent queryable objects that are all bound to the source DataTable.

Applies to

Condividi tramite