如何将数据快照下载到客户端
本主题演示如何将来自服务器数据库的数据快照下载到 SQL Server Compact 客户端数据库。本主题中的示例着重介绍以下 Sync Framework 类型：
有关如何运行示例代码的信息，请参见对常见客户端与服务器同步任务进行编程中的“帮助主题中的示例应用程序”。
示例
本主题中的示例代码演示如何为 Sync Framework 示例数据库中的 Customer、OrderHeader 和 OrderDetail 表配置快照同步。有关用于指定同步方向的属性的概述，请参见如何指定快照同步、下载同步、上载同步和双向同步。
API 的要点
本节提供的代码示例指出了在快照同步中使用的 API 的要点。下面的代码示例指定了同步方向以及在客户端上创建表的方式。
SyncTable customerSyncTable = new SyncTable("Customer");
customerSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable;
customerSyncTable.SyncDirection = SyncDirection.Snapshot;
customerSyncTable.SyncGroup = customerSyncGroup;
this.Configuration.SyncTables.Add(customerSyncTable);
Dim customerSyncTable As New SyncTable("Customer")
customerSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable
customerSyncTable.SyncDirection = SyncDirection.Snapshot
customerSyncTable.SyncGroup = customerSyncGroup
Me.Configuration.SyncTables.Add(customerSyncTable)
下面的代码示例指定一条从服务器中选择行并将它们应用到客户端的命令。这是一个包括了要同步的列的 SELECT 语句。还可以将一个 WHERE 子句添加到筛选行。有关筛选的更多信息，请参见如何筛选行和列。由于在每次同步期间会完全刷新数据，因此该命令未包括仅限下载和双向同步所需的跟踪列。
SyncAdapter customerSyncAdapter = new SyncAdapter("Customer");
SqlCommand customerIncrInserts = new SqlCommand();
customerIncrInserts.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer";
customerIncrInserts.Connection = serverConn;
customerSyncAdapter.SelectIncrementalInsertsCommand = customerIncrInserts;
this.SyncAdapters.Add(customerSyncAdapter);
Dim customerSyncAdapter As New SyncAdapter("Customer")
Dim customerIncrInserts As New SqlCommand()
customerIncrInserts.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer"
customerIncrInserts.Connection = serverConn
customerSyncAdapter.SelectIncrementalInsertsCommand = customerIncrInserts
Me.SyncAdapters.Add(customerSyncAdapter)
完整的代码示例
下面的完整代码示例包括了上面介绍的代码示例以及用于执行同步的其他代码。此外，还应了解如何使用 SyncStatistics 显示与同步会话有关的信息。示例需要 Utility 类，可通过用于数据库提供程序帮助主题的 Utility 类获得该类。
using System;
using System.IO;
using System.Text;
using System.Data;
using System.Data.SqlClient;
using System.Data.SqlServerCe;
using Microsoft.Synchronization;
using Microsoft.Synchronization.Data;
using Microsoft.Synchronization.Data.Server;
using Microsoft.Synchronization.Data.SqlServerCe;
namespace Microsoft.Samples.Synchronization
{
class Program
{
static void Main(string[] args)
{
//The SampleStats class handles information from the SyncStatistics
//object that the Synchronize method returns.
SampleStats sampleStats = new SampleStats();
//Request a password for the client database, and delete
//and re-create the database. The client synchronization
//provider also enables you to create the client database
//if it does not exist.
Utility.SetPassword_SqlCeClientSync();
Utility.DeleteAndRecreateCompactDatabase(Utility.ConnStr_SqlCeClientSync, true);
//Initial synchronization. Instantiate the SyncAgent
//and call Synchronize.
SampleSyncAgent sampleSyncAgent = new SampleSyncAgent();
SyncStatistics syncStatistics = sampleSyncAgent.Synchronize();
sampleStats.DisplayStats(syncStatistics, "initial");
//Make changes on the server.
Utility.MakeDataChangesOnServer("Customer");
//Subsequent synchronization. There was one insert,
//one update, and one delete made on the server;
//therefore, the row count is identical, but the
//data is different.
syncStatistics = sampleSyncAgent.Synchronize();
sampleStats.DisplayStats(syncStatistics, "subsequent");
//Return server data back to its original state.
Utility.CleanUpServer();
//Exit.
Console.Write("\nPress Enter to close the window.");
Console.ReadLine();
}
}
//Create a class that is derived from
//Microsoft.Synchronization.SyncAgent.
public class SampleSyncAgent : SyncAgent
{
public SampleSyncAgent()
{
//Instantiate a client synchronization provider and specify it
//as the local provider for this synchronization agent.
this.LocalProvider = new SampleClientSyncProvider();
//Instantiate a server synchronization provider and specify it
//as the remote provider for this synchronization agent.
this.RemoteProvider = new SampleServerSyncProvider();
//Create two SyncGroups so that changes to OrderHeader
//and OrderDetail are made in one transaction. Depending on
//application requirements, you might include Customer
//in the same group.
SyncGroup customerSyncGroup = new SyncGroup("Customer");
SyncGroup orderSyncGroup = new SyncGroup("Order");
//Add each table: specify a synchronization direction of
//Snapshot, and that any existing tables should be dropped.
SyncTable customerSyncTable = new SyncTable("Customer");
customerSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable;
customerSyncTable.SyncDirection = SyncDirection.Snapshot;
customerSyncTable.SyncGroup = customerSyncGroup;
this.Configuration.SyncTables.Add(customerSyncTable);
SyncTable orderHeaderSyncTable = new SyncTable("OrderHeader");
orderHeaderSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable;
orderHeaderSyncTable.SyncDirection = SyncDirection.Snapshot;
orderHeaderSyncTable.SyncGroup = orderSyncGroup;
this.Configuration.SyncTables.Add(orderHeaderSyncTable);
SyncTable orderDetailSyncTable = new SyncTable("OrderDetail");
orderDetailSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable;
orderDetailSyncTable.SyncDirection = SyncDirection.Snapshot;
orderDetailSyncTable.SyncGroup = orderSyncGroup;
this.Configuration.SyncTables.Add(orderDetailSyncTable);
}
}
//Create a class that is derived from
//Microsoft.Synchronization.Server.DbServerSyncProvider.
public class SampleServerSyncProvider : DbServerSyncProvider
{
public SampleServerSyncProvider()
{
//Create a connection to the sample server database.
Utility util = new Utility();
SqlConnection serverConn = new SqlConnection(Utility.ConnStr_DbServerSync);
this.Connection = serverConn;
//Create a SyncAdapter for each table, and then define
//the command to select rows from the table. With the Snapshot
//option, you do not download incremental changes. However,
//you still use the SelectIncrementalInsertsCommand to select
//the rows to download for each snapshot. The commands include
//only those columns that you want on the client.
//Customer table.
SyncAdapter customerSyncAdapter = new SyncAdapter("Customer");
SqlCommand customerIncrInserts = new SqlCommand();
customerIncrInserts.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer";
customerIncrInserts.Connection = serverConn;
customerSyncAdapter.SelectIncrementalInsertsCommand = customerIncrInserts;
this.SyncAdapters.Add(customerSyncAdapter);
//OrderHeader table.
SyncAdapter orderHeaderSyncAdapter = new SyncAdapter("OrderHeader");
SqlCommand orderHeaderIncrInserts = new SqlCommand();
orderHeaderIncrInserts.CommandText =
"SELECT OrderId, CustomerId, OrderDate, OrderStatus " +
"FROM Sales.OrderHeader";
orderHeaderIncrInserts.Connection = serverConn;
orderHeaderSyncAdapter.SelectIncrementalInsertsCommand = orderHeaderIncrInserts;
this.SyncAdapters.Add(orderHeaderSyncAdapter);
//OrderDetail table.
SyncAdapter orderDetailSyncAdapter = new SyncAdapter("OrderDetail");
SqlCommand orderDetailIncrInserts = new SqlCommand();
orderDetailIncrInserts.CommandText =
"SELECT OrderDetailId, OrderId, Product, Quantity " +
"FROM Sales.OrderDetail";
orderDetailIncrInserts.Connection = serverConn;
orderDetailSyncAdapter.SelectIncrementalInsertsCommand = orderDetailIncrInserts;
this.SyncAdapters.Add(orderDetailSyncAdapter);
}
}
//Create a class that is derived from
//Microsoft.Synchronization.Data.SqlServerCe.SqlCeClientSyncProvider.
//You can just instantiate the provider directly and associate it
//with the SyncAgent, but you could use this class to handle client
//provider events and other client-side processing.
public class SampleClientSyncProvider : SqlCeClientSyncProvider
{
public SampleClientSyncProvider()
{
//Specify a connection string for the sample client database.
Utility util = new Utility();
this.ConnectionString = Utility.ConnStr_SqlCeClientSync;
}
}
//Handle the statistics that are returned by the SyncAgent.
public class SampleStats
{
public void DisplayStats(SyncStatistics syncStatistics, string syncType)
{
Console.WriteLine(String.Empty);
if (syncType == "initial")
{
Console.WriteLine("****** Initial Synchronization ******");
}
else if (syncType == "subsequent")
{
Console.WriteLine("***** Subsequent Synchronization ****");
}
Console.WriteLine("Start Time: " + syncStatistics.SyncStartTime);
Console.WriteLine("Total Changes Downloaded: " + syncStatistics.TotalChangesDownloaded);
Console.WriteLine("Complete Time: " + syncStatistics.SyncCompleteTime);
Console.WriteLine(String.Empty);
}
}
}
Imports System
Imports System.IO
Imports System.Text
Imports System.Data
Imports System.Data.SqlClient
Imports System.Data.SqlServerCe
Imports Microsoft.Synchronization
Imports Microsoft.Synchronization.Data
Imports Microsoft.Synchronization.Data.Server
Imports Microsoft.Synchronization.Data.SqlServerCe
Class Program
Shared Sub Main(ByVal args() As String)
'The SampleStats class handles information from the SyncStatistics
'object that the Synchronize method returns.
Dim sampleStats As New SampleStats()
'Request a password for the client database, and delete
'and re-create the database. The client synchronization
'provider also enables you to create the client database
'if it does not exist.
Utility.SetPassword_SqlCeClientSync()
Utility.DeleteAndRecreateCompactDatabase(Utility.ConnStr_SqlCeClientSync, True)
'Initial synchronization. Instantiate the SyncAgent
'and call Synchronize.
Dim sampleSyncAgent As New SampleSyncAgent()
Dim syncStatistics As SyncStatistics = sampleSyncAgent.Synchronize()
sampleStats.DisplayStats(syncStatistics, "initial")
'Make changes on the server.
Utility.MakeDataChangesOnServer("Customer")
'Subsequent synchronization. There was one insert,
'one update, and one delete made on the server;
'therefore, the row count is identical, but the
'data is different.
syncStatistics = sampleSyncAgent.Synchronize()
sampleStats.DisplayStats(syncStatistics, "subsequent")
'Return server data back to its original state.
Utility.CleanUpServer()
'Exit.
Console.Write(vbLf + "Press Enter to close the window.")
Console.ReadLine()
End Sub 'Main
End Class 'Program
'Create a class that is derived from
'Microsoft.Synchronization.SyncAgent.
Public Class SampleSyncAgent
Inherits SyncAgent
Public Sub New()
'Instantiate a client synchronization provider and specify it
'as the local provider for this synchronization agent.
Me.LocalProvider = New SampleClientSyncProvider()
'Instantiate a server synchronization provider and specify it
'as the remote provider for this synchronization agent.
Me.RemoteProvider = New SampleServerSyncProvider()
'Create two SyncGroups so that changes to OrderHeader
'and OrderDetail are made in one transaction. Depending on
'application requirements, you might include Customer
'in the same group.
Dim customerSyncGroup As New SyncGroup("Customer")
Dim orderSyncGroup As New SyncGroup("Order")
'Add each table: specify a synchronization direction of
'Snapshot, and that any existing tables should be dropped.
Dim customerSyncTable As New SyncTable("Customer")
customerSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable
customerSyncTable.SyncDirection = SyncDirection.Snapshot
customerSyncTable.SyncGroup = customerSyncGroup
Me.Configuration.SyncTables.Add(customerSyncTable)
Dim orderHeaderSyncTable As New SyncTable("OrderHeader")
orderHeaderSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable
orderHeaderSyncTable.SyncDirection = SyncDirection.Snapshot
orderHeaderSyncTable.SyncGroup = orderSyncGroup
Me.Configuration.SyncTables.Add(orderHeaderSyncTable)
Dim orderDetailSyncTable As New SyncTable("OrderDetail")
orderDetailSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable
orderDetailSyncTable.SyncDirection = SyncDirection.Snapshot
orderDetailSyncTable.SyncGroup = orderSyncGroup
Me.Configuration.SyncTables.Add(orderDetailSyncTable)
End Sub 'New
End Class 'SampleSyncAgent
'Create a class that is derived from
'Microsoft.Synchronization.Server.DbServerSyncProvider.
Public Class SampleServerSyncProvider
Inherits DbServerSyncProvider
Public Sub New()
'Create a connection to the sample server database.
Dim util As New Utility()
Dim serverConn As New SqlConnection(Utility.ConnStr_DbServerSync)
Me.Connection = serverConn
'Create a SyncAdapter for each table, and then define
'the command to select rows from the table. With the Snapshot
'option, you do not download incremental changes. However,
'you still use the SelectIncrementalInsertsCommand to select
'the rows to download for each snapshot. The commands include
'only those columns that you want on the client.
'Customer table.
Dim customerSyncAdapter As New SyncAdapter("Customer")
Dim customerIncrInserts As New SqlCommand()
customerIncrInserts.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer"
customerIncrInserts.Connection = serverConn
customerSyncAdapter.SelectIncrementalInsertsCommand = customerIncrInserts
Me.SyncAdapters.Add(customerSyncAdapter)
'OrderHeader table.
Dim orderHeaderSyncAdapter As New SyncAdapter("OrderHeader")
Dim orderHeaderIncrInserts As New SqlCommand()
orderHeaderIncrInserts.CommandText = _
"SELECT OrderId, CustomerId, OrderDate, OrderStatus " _
& "FROM Sales.OrderHeader"
orderHeaderIncrInserts.Connection = serverConn
orderHeaderSyncAdapter.SelectIncrementalInsertsCommand = orderHeaderIncrInserts
Me.SyncAdapters.Add(orderHeaderSyncAdapter)
'OrderDetail table.
Dim orderDetailSyncAdapter As New SyncAdapter("OrderDetail")
Dim orderDetailIncrInserts As New SqlCommand()
orderDetailIncrInserts.CommandText = _
"SELECT OrderDetailId, OrderId, Product, Quantity " _
& "FROM Sales.OrderDetail"
orderDetailIncrInserts.Connection = serverConn
orderDetailSyncAdapter.SelectIncrementalInsertsCommand = orderDetailIncrInserts
Me.SyncAdapters.Add(orderDetailSyncAdapter)
End Sub 'New
End Class 'SampleServerSyncProvider
'Create a class that is derived from
'Microsoft.Synchronization.Data.SqlServerCe.SqlCeClientSyncProvider.
'You can just instantiate the provider directly and associate it
'with the SyncAgent, but you could use this class to handle client
'provider events and other client-side processing.
Public Class SampleClientSyncProvider
Inherits SqlCeClientSyncProvider
Public Sub New()
'Specify a connection string for the sample client database.
Dim util As New Utility()
Me.ConnectionString = Utility.ConnStr_SqlCeClientSync
End Sub 'New
End Class 'SampleClientSyncProvider
'Handle the statistics that are returned by the SyncAgent.
Public Class SampleStats
Public Sub DisplayStats(ByVal syncStatistics As SyncStatistics, ByVal syncType As String)
Console.WriteLine(String.Empty)
If syncType = "initial" Then
Console.WriteLine("****** Initial Synchronization ******")
ElseIf syncType = "subsequent" Then
Console.WriteLine("***** Subsequent Synchronization ****")
End If
Console.WriteLine("Start Time: " & syncStatistics.SyncStartTime)
Console.WriteLine("Total Changes Downloaded: " & syncStatistics.TotalChangesDownloaded)
Console.WriteLine("Complete Time: " & syncStatistics.SyncCompleteTime)
Console.WriteLine(String.Empty)
End Sub 'DisplayStats
End Class 'SampleStats