Caricamento di dati in un dataset
Prima di poter eseguire query su di esso con LINQ to DataSet, è necessario popolare un oggetto DataSet. Sono disponibili diversi modi per popolare DataSet. Ad esempio, è possibile usare LINQ to SQL per eseguire query sul database e caricare i risultati in DataSet. Per altre informazioni, vedere LINQ to SQL.
Per caricare i dati in DataSet, è inoltre usare la classe DataAdapter per recuperare i dati dal database, Questo è illustrato nell'esempio seguente.
Esempio
In questo esempio viene usato un oggetto DataAdapter per eseguire una query sul database AdventureWorks relativa alle informazioni sulle vendite dell'anno 2002. I risultati vengono quindi caricati in un oggetto DataSet. Dopo aver popolato DataSet, è possibile scrivere query da eseguire su di esso con LINQ to DataSet. Il metodo FillDataSet in questo esempio viene usato nelle query di esempio negli esempi di LINQ to DataSet. Per altre informazioni, vedere Esecuzione di query sui DataSet.
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