Exemplos de sintaxe da consulta com base em método: Definir operadores (LINQ to DataSet)
Os exemplos neste tópico demonstram como usar os operadores e Distinct, Except, Intersect e Unionpara executar operações de comparação baseadas em valor em conjuntos de linhas de dados.Carregando dados em um conjunto de dados Consulte Comparando DataRows para obter mais informações sobre DataRowComparer.
O método FillDataSet usado nesses exemplos é especificado em Carregar dados em um DataSet.
Os exemplos neste tópico usam as tabelas Contact, Address, Product, SalesOrderHeader e SalesOrderDetail no banco de dados de exemplo AdventureWorks.
Os exemplos deste tópico usam as seguintes instruções using/Imports:
using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Globalization;
using System.Linq;
using System.Windows.Forms;
Option Explicit On
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
Para obter mais informações, consulte Como: criar um projeto do LINQ to DataSet no Visual Studio.
Distinct
Exemplo
Este exemplo usa o método de Distinct para remover elementos duplicados em uma sequência.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
List<DataRow> rows = new List<DataRow>();
DataTable contact = ds.Tables["Contact"];
// Get 100 rows from the Contact table.
IEnumerable<DataRow> query = (from c in contact.AsEnumerable()
select c).Take(100);
DataTable contactsTableWith100Rows = query.CopyToDataTable();
// Add 100 rows to the list.
foreach (DataRow row in contactsTableWith100Rows.Rows)
rows.Add(row);
// Create duplicate rows by adding the same 100 rows to the list.
foreach (DataRow row in contactsTableWith100Rows.Rows)
rows.Add(row);
DataTable table =
System.Data.DataTableExtensions.CopyToDataTable<DataRow>(rows);
// Find the unique contacts in the table.
IEnumerable<DataRow> uniqueContacts =
table.AsEnumerable().Distinct(DataRowComparer.Default);
Console.WriteLine("Unique contacts:");
foreach (DataRow uniqueContact in uniqueContacts)
{
Console.WriteLine(uniqueContact.Field<Int32>("ContactID"));
}
' 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 rows As List(Of DataRow) = New List(Of DataRow)
Dim contacts As DataTable = ds.Tables("Contact")
' Get 100 rows from the Contact table.
Dim query = ( _
From c In contacts.AsEnumerable() _
Select c).Take(100)
Dim contactsTableWith100Rows = query.CopyToDataTable()
' Add 100 rows to the list.
For Each row In contactsTableWith100Rows.Rows
rows.Add(row)
Next
' Create duplicate rows by adding the same 100 rows to the list.
For Each row In contactsTableWith100Rows.Rows
rows.Add(row)
Next
Dim table = _
System.Data.DataTableExtensions.CopyToDataTable(Of DataRow)(rows)
' Find the unique contacts in the table.
Dim uniqueContacts = _
table.AsEnumerable().Distinct(DataRowComparer.Default)
Console.WriteLine("Unique contacts:")
For Each uniqueContact In uniqueContacts
Console.WriteLine(uniqueContact.Field(Of Integer)("ContactID"))
Next
Except
Exemplo
Este exemplo usa o método de Except para retornar os contatos que aparecem na primeira tabela mas não no segundo.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable contactTable = ds.Tables["Contact"];
// Create two tables.
IEnumerable<DataRow> query1 = from contact in contactTable.AsEnumerable()
where contact.Field<string>("Title") == "Ms."
select contact;
IEnumerable<DataRow> query2 = from contact in contactTable.AsEnumerable()
where contact.Field<string>("FirstName") == "Sandra"
select contact;
DataTable contacts1 = query1.CopyToDataTable();
DataTable contacts2 = query2.CopyToDataTable();
// Find the contacts that are in the first
// table but not the second.
var contacts = contacts1.AsEnumerable().Except(contacts2.AsEnumerable(),
DataRowComparer.Default);
Console.WriteLine("Except of employees tables");
foreach (DataRow row in contacts)
{
Console.WriteLine("Id: {0} {1} {2} {3}",
row["ContactID"], row["Title"], row["FirstName"], row["LastName"]);
}
' 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 query1 = _
From contact In contactTable.AsEnumerable() _
Where contact.Field(Of String)("Title") = "Ms." _
Select contact
Dim query2 = _
From contact In contactTable.AsEnumerable() _
Where contact.Field(Of String)("FirstName") = "Sandra" _
Select contact
Dim contacts1 = query1.CopyToDataTable()
Dim contacts2 = query2.CopyToDataTable()
' Find the contacts that are in the first
' table but not the second.
Dim contacts = contacts1.AsEnumerable().Except(contacts2.AsEnumerable(), _
DataRowComparer.Default)
Console.WriteLine("Except of employees tables")
For Each row In contacts
Console.WriteLine("Id: {0} {1} {2} {3}", _
row("ContactID"), row("Title"), row("FirstName"), row("LastName"))
Next
Intersect
Exemplo
Este exemplo usa o método de Intersect para retornar os contatos que aparecem em ambas as tabelas.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
DataTable contactTable = ds.Tables["Contact"];
// Create two tables.
IEnumerable<DataRow> query1 = from contact in contactTable.AsEnumerable()
where contact.Field<string>("Title") == "Ms."
select contact;
IEnumerable<DataRow> query2 = from contact in contactTable.AsEnumerable()
where contact.Field<string>("FirstName") == "Sandra"
select contact;
DataTable contacts1 = query1.CopyToDataTable();
DataTable contacts2 = query2.CopyToDataTable();
// Find the intersection of the two tables.
var contacts = contacts1.AsEnumerable().Intersect(contacts2.AsEnumerable(),
DataRowComparer.Default);
Console.WriteLine("Intersection of contacts tables");
foreach (DataRow row in contacts)
{
Console.WriteLine("Id: {0} {1} {2} {3}",
row["ContactID"], row["Title"], row["FirstName"], row["LastName"]);
}
' 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 query1 = _
From contact In contactTable.AsEnumerable() _
Where contact.Field(Of String)("Title") = "Ms." _
Select contact
Dim query2 = _
From contact In contactTable.AsEnumerable() _
Where contact.Field(Of String)("FirstName") = "Sandra" _
Select contact
Dim contacts1 = query1.CopyToDataTable()
Dim contacts2 = query2.CopyToDataTable()
Dim contacts = contacts1.AsEnumerable() _
.Intersect(contacts2.AsEnumerable(), DataRowComparer.Default)
Console.WriteLine("Intersect of employees tables")
For Each row In contacts
Console.WriteLine("Id: {0} {1} {2} {3}", _
row("ContactID"), row("Title"), row("FirstName"), row("LastName"))
Next
Union
Exemplo
Este exemplo usa o método de Union para retornar contatos exclusivos de uma das duas tabelas.
// Fill the DataSet.
DataSet ds = new DataSet();
ds.Locale = CultureInfo.InvariantCulture;
FillDataSet(ds);
// Create two tables.
DataTable contactTable = ds.Tables["Contact"];
IEnumerable<DataRow> query1 = from contact in contactTable.AsEnumerable()
where contact.Field<string>("Title") == "Ms."
select contact;
IEnumerable<DataRow> query2 = from contact in contactTable.AsEnumerable()
where contact.Field<string>("FirstName") == "Sandra"
select contact;
DataTable contacts1 = query1.CopyToDataTable();
DataTable contacts2 = query2.CopyToDataTable();
// Find the union of the two tables.
var contacts = contacts1.AsEnumerable().Union(contacts2.AsEnumerable(),
DataRowComparer.Default);
Console.WriteLine("Union of contacts tables:");
foreach (DataRow row in contacts)
{
Console.WriteLine("Id: {0} {1} {2} {3}",
row["ContactID"], row["Title"], row["FirstName"], row["LastName"]);
}
' 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 query1 = _
From contact In contactTable.AsEnumerable() _
Where contact.Field(Of String)("Title") = "Ms." _
Select contact
Dim query2 = _
From contact In contactTable.AsEnumerable() _
Where contact.Field(Of String)("FirstName") = "Sandra" _
Select contact
Dim contacts1 = query1.CopyToDataTable()
Dim contacts2 = query2.CopyToDataTable()
Dim contacts = contacts1.AsEnumerable().Union(contacts2.AsEnumerable(), _
DataRowComparer.Default)
Console.WriteLine("Union of employees tables")
For Each row In contacts
Console.WriteLine("Id: {0} {1} {2} {3}", _
row("ContactID"), row("Title"), row("FirstName"), row("LastName"))
Next