DataSet-Specific Operator Examples (LINQ to DataSet)
The examples in this topic demonstrate how to use the CopyToDataTable method and the DataRowComparer class.
The FillDataSet method used in these examples is specified in Loading Data Into a DataSet.
The examples in this topic use the Contact, Address, Product, SalesOrderHeader, and SalesOrderDetail tables in the AdventureWorks sample database.
The examples in this topic use the following using/Imports statements:
Option Explicit On
Imports System
Imports System.Linq
Imports System.Linq.Expressions
Imports System.Collections.Generic
Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.Common
Imports System.Globalization
using System;
using System.Linq;
using System.Linq.Expressions;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Data.Common;
using System.Globalization;
For more information, see How to: Create a LINQ to DataSet Project In Visual Studio.
CopyToDataTable
Example
This example loads a DataTable with query results by using the CopyToDataTable method.
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
Dim contactTable As DataTable = ds.Tables("Contact")
Dim query = _
From contact In contactTable.AsEnumerable() _
Where contact.Field(Of String)("Title") = "Ms." _
And contact.Field(Of String)("FirstName") = "Carla" _
Select contact
Dim contacts = query.CopyToDataTable().AsEnumerable()
For Each contact In contacts
Console.Write("ID: " & contact.Field(Of Integer)("ContactID"))
Console.WriteLine(" Name: " & contact.Field(Of String)("LastName") & _
", " & contact.Field(Of String)("FirstName"))
Next
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable contacts1 = ds.Tables["Contact"];
IEnumerable<DataRow> query =
from contact in contacts1.AsEnumerable()
where contact.Field<string>("Title") == "Ms."
&& contact.Field<string>("FirstName") == "Carla"
select contact;
DataTable contacts2 = query.CopyToDataTable();
foreach (DataRow contact in contacts2.AsEnumerable())
{
Console.WriteLine("ID:{0} Name: {1}, {2}",
contact.Field<Int32>("ContactID"),
contact.Field<string>("LastName"),
contact.Field<string>("FirstName"));
}
DataRowComparer
Example
This example compares two different data rows by using DataRowComparer.
' Fill the DataSet.
Dim ds As New DataSet()
ds.Locale = CultureInfo.InvariantCulture
' See the FillDataSet method in the Loading Data Into a DataSet topic.
FillDataSet(ds)
' Get two rows from the SalesOrderHeader table.
Dim table As DataTable = ds.Tables("SalesOrderHeader")
Dim left = table.Rows(0)
Dim right = table.Rows(1)
' Compare the two different rows.
Dim comparer As IEqualityComparer(Of DataRow) = DataRowComparer.Default
Dim bEqual = comparer.Equals(left, right)
If (bEqual = True) Then
Console.WriteLine("Two rows are equal")
Else
Console.WriteLine("Two rows are not equal")
End If
' Output the hash codes of the two rows.
Console.WriteLine("The hashcodes for the two rows are {0}, {1}", _
comparer.GetHashCode(left), _
comparer.GetHashCode(right))
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
// Get two rows from the SalesOrderHeader table.
DataTable table = ds.Tables["SalesOrderHeader"];
DataRow left = (DataRow)table.Rows[0];
DataRow right = (DataRow)table.Rows[1];
// Compare the two different rows.
IEqualityComparer<DataRow> comparer = DataRowComparer.Default;
bool bEqual = comparer.Equals(left, right);
if (bEqual)
Console.WriteLine("The two rows are equal");
else
Console.WriteLine("The two rows are not equal");
// Get the hash codes of the two rows.
Console.WriteLine("The hashcodes for the two rows are {0}, {1}",
comparer.GetHashCode(left),
comparer.GetHashCode(right));