Laden von Daten in ein DataSet
Ein DataSet-Objekt muss zuerst aufgefüllt werden, bevor Sie es mit LINQ to DataSet abfragen können. Das Auffüllen des DataSet-Objekts kann auf verschiedene Art und Weise erfolgen. So können Sie z. B. LINQ to SQL verwenden, um die Datenbank abzufragen und die Ergebnisse in das DataSet zu laden. Weitere Informationen finden Sie unter LINQ to SQL.
Eine andere Möglichkeit, Daten in ein DataSet zu laden, besteht darin, Daten mithilfe der DataAdapter-Klasse aus der Datenbank abzurufen. Dies wird im folgenden Beispiel veranschaulicht.
Beispiel
In diesem Beispiel wird ein DataAdapter verwendet, um aus der <legacyBold>AdventureWorks</legacyBold>-Datenbank Verkaufsinformationen für das Jahr 2002 abzurufen und die Ergebnisse in ein DataSet zu laden. Sobald das DataSet aufgefüllt ist, können Sie mithilfe von LINQ to DataSet Abfragen dafür schreiben. Die FillDataSet-Methode in diesem Beispiel wird in den Beispielabfragen in Beispiele für LINQ to DataSet verwendet. Weitere Informationen finden Sie unter Abfragen von DataSets.
try
{
// Create a new adapter and give it a query to fetch sales order, contact,
// address, and product information for sales in the year 2002. Point connection
// information to the configuration setting "AdventureWorks".
string connectionString = "Data Source=localhost;Initial Catalog=AdventureWorks;"
+ "Integrated Security=true;";
SqlDataAdapter da = new SqlDataAdapter(
"SELECT SalesOrderID, ContactID, OrderDate, OnlineOrderFlag, " +
"TotalDue, SalesOrderNumber, Status, ShipToAddressID, BillToAddressID " +
"FROM Sales.SalesOrderHeader " +
"WHERE DATEPART(YEAR, OrderDate) = @year; " +
"SELECT d.SalesOrderID, d.SalesOrderDetailID, d.OrderQty, " +
"d.ProductID, d.UnitPrice " +
"FROM Sales.SalesOrderDetail d " +
"INNER JOIN Sales.SalesOrderHeader h " +
"ON d.SalesOrderID = h.SalesOrderID " +
"WHERE DATEPART(YEAR, OrderDate) = @year; " +
"SELECT p.ProductID, p.Name, p.ProductNumber, p.MakeFlag, " +
"p.Color, p.ListPrice, p.Size, p.Class, p.Style, p.Weight " +
"FROM Production.Product p; " +
"SELECT DISTINCT a.AddressID, a.AddressLine1, a.AddressLine2, " +
"a.City, a.StateProvinceID, a.PostalCode " +
"FROM Person.Address a " +
"INNER JOIN Sales.SalesOrderHeader h " +
"ON a.AddressID = h.ShipToAddressID OR a.AddressID = h.BillToAddressID " +
"WHERE DATEPART(YEAR, OrderDate) = @year; " +
"SELECT DISTINCT c.ContactID, c.Title, c.FirstName, " +
"c.LastName, c.EmailAddress, c.Phone " +
"FROM Person.Contact c " +
"INNER JOIN Sales.SalesOrderHeader h " +
"ON c.ContactID = h.ContactID " +
"WHERE DATEPART(YEAR, OrderDate) = @year;",
connectionString);
// Add table mappings.
da.SelectCommand.Parameters.AddWithValue("@year", 2002);
da.TableMappings.Add("Table", "SalesOrderHeader");
da.TableMappings.Add("Table1", "SalesOrderDetail");
da.TableMappings.Add("Table2", "Product");
da.TableMappings.Add("Table3", "Address");
da.TableMappings.Add("Table4", "Contact");
// Fill the DataSet.
da.Fill(ds);
// Add data relations.
DataTable orderHeader = ds.Tables["SalesOrderHeader"];
DataTable orderDetail = ds.Tables["SalesOrderDetail"];
DataRelation order = new DataRelation("SalesOrderHeaderDetail",
orderHeader.Columns["SalesOrderID"],
orderDetail.Columns["SalesOrderID"], true);
ds.Relations.Add(order);
DataTable contact = ds.Tables["Contact"];
DataTable orderHeader2 = ds.Tables["SalesOrderHeader"];
DataRelation orderContact = new DataRelation("SalesOrderContact",
contact.Columns["ContactID"],
orderHeader2.Columns["ContactID"], true);
ds.Relations.Add(orderContact);
}
catch (SqlException ex)
{
Console.WriteLine("SQL exception occurred: " + ex.Message);
}
Try
Dim connectionString As String
connectionString = "Data Source=localhost;Initial Catalog=AdventureWorks;" & _
"Integrated Security=true;"
' Create a new adapter and give it a query to fetch sales order, contact,
' address, and product information for sales in the year 2002. Point connection
' information to the configuration setting "AdventureWorks".
Dim da = New SqlDataAdapter( _
"SELECT SalesOrderID, ContactID, OrderDate, OnlineOrderFlag, " & _
"TotalDue, SalesOrderNumber, Status, ShipToAddressID, BillToAddressID " & _
"FROM Sales.SalesOrderHeader " & _
"WHERE DATEPART(YEAR, OrderDate) = @year; " & _
"SELECT d.SalesOrderID, d.SalesOrderDetailID, d.OrderQty, " & _
"d.ProductID, d.UnitPrice " & _
"FROM Sales.SalesOrderDetail d " & _
"INNER JOIN Sales.SalesOrderHeader h " & _
"ON d.SalesOrderID = h.SalesOrderID " & _
"WHERE DATEPART(YEAR, OrderDate) = @year; " & _
"SELECT p.ProductID, p.Name, p.ProductNumber, p.MakeFlag, " & _
"p.Color, p.ListPrice, p.Size, p.Class, p.Style " & _
"FROM Production.Product p; " & _
"SELECT DISTINCT a.AddressID, a.AddressLine1, a.AddressLine2, " & _
"a.City, a.StateProvinceID, a.PostalCode " & _
"FROM Person.Address a " & _
"INNER JOIN Sales.SalesOrderHeader h " & _
"ON a.AddressID = h.ShipToAddressID OR a.AddressID = h.BillToAddressID " & _
"WHERE DATEPART(YEAR, OrderDate) = @year; " & _
"SELECT DISTINCT c.ContactID, c.Title, c.FirstName, " & _
"c.LastName, c.EmailAddress, c.Phone " & _
"FROM Person.Contact c " & _
"INNER JOIN Sales.SalesOrderHeader h " & _
"ON c.ContactID = h.ContactID " & _
"WHERE DATEPART(YEAR, OrderDate) = @year;", _
connectionString)
' Add table mappings.
da.SelectCommand.Parameters.AddWithValue("@year", 2002)
da.TableMappings.Add("Table", "SalesOrderHeader")
da.TableMappings.Add("Table1", "SalesOrderDetail")
da.TableMappings.Add("Table2", "Product")
da.TableMappings.Add("Table3", "Address")
da.TableMappings.Add("Table4", "Contact")
da.Fill(ds)
' Add data relations.
Dim orderHeader As DataTable = ds.Tables("SalesOrderHeader")
Dim orderDetail As DataTable = ds.Tables("SalesOrderDetail")
Dim co As DataRelation = New DataRelation("SalesOrderHeaderDetail", _
orderHeader.Columns("SalesOrderID"), _
orderDetail.Columns("SalesOrderID"), True)
ds.Relations.Add(co)
Dim contact As DataTable = ds.Tables("Contact")
Dim orderContact As DataRelation = New DataRelation("SalesOrderContact", _
contact.Columns("ContactID"), _
orderHeader.Columns("ContactID"), True)
ds.Relations.Add(orderContact)
Catch ex As SqlException
Console.WriteLine("SQL exception occurred: " & ex.Message)
End Try