HOW TO：下載累加資料變更至用戶端
本主題示範如何從伺服器資料庫下載累加資料變更至 SQL Server Compact 用戶端資料庫。本主題的範例將重點放在下列的 Sync Framework 型別：
如需有關如何執行範例程式碼的詳細資訊，請參閱撰寫一般用戶端和伺服器同步處理工作中的＜HOW-TO 主題中的範例應用程式＞。
範例
此主題中的範例程式碼示範如何從 Sync Framework 範例資料庫當中，為 Customer 資料表設定僅限下載的同步處理。如需用於指定同步處理方向的屬性概觀，請參閱 HOW TO：指定快照集、下載、上傳及雙向同步處理。
僅限下載的同步處理需要在伺服器資料庫中追蹤累加資料，並套用至用戶端資料庫。Sync Framework 會處理用戶端資料庫。然而，您必須先設定伺服器資料庫，並指定要從伺服器資料庫選取變更的命令。範例程式碼中包含了這些命令。如需有關如何設定伺服器資料庫的詳細資訊，請參閱 追蹤伺服器資料庫中的變更。
API 的主要部分
本節提供的程式碼範例將指出用於進行僅限下載之同步處理的 API 主要部分。下列程式碼範例指出同步處理的方向，以及如何在用戶端建立資料表。
SyncTable customerSyncTable = new SyncTable("Customer");
customerSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable;
customerSyncTable.SyncDirection = SyncDirection.DownloadOnly;
customerSyncTable.SyncGroup = customerSyncGroup;
this.Configuration.SyncTables.Add(customerSyncTable);
Dim customerSyncTable As New SyncTable("Customer")
customerSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable
customerSyncTable.SyncDirection = SyncDirection.DownloadOnly
customerSyncTable.SyncGroup = customerSyncGroup
Me.Configuration.SyncTables.Add(customerSyncTable)
下列程式碼範例指出可從伺服器擷取新的錨定值的命令。在這個案例中，系統會擷取時間戳記值，並儲存於用戶端資料庫。在每一次的同步處理期間，會使用新的錨定值和來自上一個同步處理的最後一個錨定值：同步處理這些上限與下限之間的變更集。您會看見用來從伺服器資料庫中選取變更的命令中使用了錨定參數。
SqlCommand selectNewAnchorCommand = new SqlCommand();
string newAnchorVariable = "@" + SyncSession.SyncNewReceivedAnchor;
selectNewAnchorCommand.CommandText =
"SELECT " + newAnchorVariable + " = min_active_rowversion() - 1";
selectNewAnchorCommand.Parameters.Add(newAnchorVariable, SqlDbType.Timestamp);
selectNewAnchorCommand.Parameters[newAnchorVariable].Direction = ParameterDirection.Output;
selectNewAnchorCommand.Connection = serverConn;
this.SelectNewAnchorCommand = selectNewAnchorCommand;
Dim selectNewAnchorCommand As New SqlCommand()
Dim newAnchorVariable As String = "@" + SyncSession.SyncNewReceivedAnchor
With selectNewAnchorCommand
.CommandText = "SELECT " + newAnchorVariable + " = min_active_rowversion() - 1"
.Parameters.Add(newAnchorVariable, SqlDbType.Timestamp)
.Parameters(newAnchorVariable).Direction = ParameterDirection.Output
.Connection = serverConn
End With
Me.SelectNewAnchorCommand = selectNewAnchorCommand
下列程式碼範例會指定一個命令，以便從伺服器選取要套用至用戶端的累加更新。這是 SELECT 陳述式，當中包含要進行同步的資料行。其中也有一個使用追蹤資料行和 SelectNewAnchorCommand 擷取的錨定值的 WHERE 子句。如需錨定和其他工作階段 (Session) 變數的詳細資訊，請參閱 HOW TO：使用工作階段變數。如需有關如何篩選已下載資料的詳細資訊，請參閱 HOW TO：篩選資料列和資料行。
SqlCommand customerIncrUpdates = new SqlCommand();
customerIncrUpdates.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer " +
"WHERE (UpdateTimestamp > @sync_last_received_anchor " +
"AND UpdateTimestamp <= @sync_new_received_anchor " +
"AND NOT (InsertTimestamp > @sync_last_received_anchor))";
customerIncrUpdates.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp);
customerIncrUpdates.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp);
customerIncrUpdates.Connection = serverConn;
customerSyncAdapter.SelectIncrementalUpdatesCommand = customerIncrUpdates;
Dim customerIncrUpdates As New SqlCommand()
With customerIncrUpdates
.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer " _
& "WHERE (UpdateTimestamp > @sync_last_received_anchor " _
& "AND UpdateTimestamp <= @sync_new_received_anchor " _
& "AND NOT (InsertTimestamp > @sync_last_received_anchor))"
.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp)
.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp)
.Connection = serverConn
End With
customerSyncAdapter.SelectIncrementalUpdatesCommand = customerIncrUpdates
完整的程式碼範例
下列的完整程式碼範例包含先前所述的程式碼範例，以及其他的程式碼，可用來執行同步處理。同時請注意範例中是如何使用 SyncStatistics 來顯示有關同步處理工作階段的資訊。此範例需要 Utility 類別，詳情請參閱資料庫提供者公用程式類別的 HOW-TO 主題。
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.
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 a Customer SyncGroup. This is not required
//for the single table we are synchronizing; it is typically
//used so that changes to multiple related tables are
//synchronized at the same time.
SyncGroup customerSyncGroup = new SyncGroup("Customer");
//Add the Customer table: specify a synchronization direction of
//DownloadOnly and that an existing table should be dropped.
SyncTable customerSyncTable = new SyncTable("Customer");
customerSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable;
customerSyncTable.SyncDirection = SyncDirection.DownloadOnly;
customerSyncTable.SyncGroup = customerSyncGroup;
this.Configuration.SyncTables.Add(customerSyncTable);
}
}
//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 command to retrieve a new anchor value from
//the server. In this case, we use a timestamp value
//that is retrieved and stored in the client database.
//During each synchronization, the new anchor value and
//the last anchor value from the previous synchronization
//are used: the set of changes between these upper and
//lower bounds is synchronized.
//
//SyncSession.SyncNewReceivedAnchor is a string constant;
//you could also use @sync_new_received_anchor directly in
//your queries.
SqlCommand selectNewAnchorCommand = new SqlCommand();
string newAnchorVariable = "@" + SyncSession.SyncNewReceivedAnchor;
selectNewAnchorCommand.CommandText =
"SELECT " + newAnchorVariable + " = min_active_rowversion() - 1";
selectNewAnchorCommand.Parameters.Add(newAnchorVariable, SqlDbType.Timestamp);
selectNewAnchorCommand.Parameters[newAnchorVariable].Direction = ParameterDirection.Output;
selectNewAnchorCommand.Connection = serverConn;
this.SelectNewAnchorCommand = selectNewAnchorCommand;
//Create a SyncAdapter for the Customer table, and then define
//the commands to synchronize changes:
//* SelectIncrementalInsertsCommand, SelectIncrementalUpdatesCommand,
// and SelectIncrementalDeletesCommand are used to select changes
// from the server that the client provider then applies to the client.
//Create the SyncAdapter.
SyncAdapter customerSyncAdapter = new SyncAdapter("Customer");
//Select inserts from the server.
SqlCommand customerIncrInserts = new SqlCommand();
customerIncrInserts.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer " +
"WHERE (InsertTimestamp > @sync_last_received_anchor " +
"AND InsertTimestamp <= @sync_new_received_anchor)";
customerIncrInserts.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp);
customerIncrInserts.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp);
customerIncrInserts.Connection = serverConn;
customerSyncAdapter.SelectIncrementalInsertsCommand = customerIncrInserts;
//Select updates from the server.
SqlCommand customerIncrUpdates = new SqlCommand();
customerIncrUpdates.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer " +
"WHERE (UpdateTimestamp > @sync_last_received_anchor " +
"AND UpdateTimestamp <= @sync_new_received_anchor " +
"AND NOT (InsertTimestamp > @sync_last_received_anchor))";
customerIncrUpdates.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp);
customerIncrUpdates.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp);
customerIncrUpdates.Connection = serverConn;
customerSyncAdapter.SelectIncrementalUpdatesCommand = customerIncrUpdates;
//Select deletes from the server.
SqlCommand customerIncrDeletes = new SqlCommand();
customerIncrDeletes.CommandText =
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " +
"FROM Sales.Customer_Tombstone " +
"WHERE (@sync_initialized = 1 " +
"AND DeleteTimestamp > @sync_last_received_anchor " +
"AND DeleteTimestamp <= @sync_new_received_anchor)";
customerIncrDeletes.Parameters.Add("@" + SyncSession.SyncInitialized, SqlDbType.Bit);
customerIncrDeletes.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp);
customerIncrDeletes.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp);
customerIncrDeletes.Connection = serverConn;
customerSyncAdapter.SelectIncrementalDeletesCommand = customerIncrDeletes;
//Add the SyncAdapter to the server synchronization provider.
this.SyncAdapters.Add(customerSyncAdapter);
}
}
//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 here we use this class to handle client
//provider events.
public class SampleClientSyncProvider : SqlCeClientSyncProvider
{
public SampleClientSyncProvider()
{
//Specify a connection string for the sample client database.
Utility util = new Utility();
this.ConnectionString = Utility.ConnStr_SqlCeClientSync;
//Unlike Bidirectional and UploadOnly synchronization, we do
//not have to make schema changes for the Customer table. In
//those scenarios, we added defaults because inserts were made
//directly into the client database. We handle the events here
//so that we can write to the screen.
this.CreatingSchema += new EventHandler<CreatingSchemaEventArgs>(SampleClientSyncProvider_CreatingSchema);
this.SchemaCreated += new EventHandler<SchemaCreatedEventArgs>(SampleClientSyncProvider_SchemaCreated);
}
private void SampleClientSyncProvider_CreatingSchema(object sender, CreatingSchemaEventArgs e)
{
Console.Write("Creating schema for " + e.Table.TableName + " | ");
}
private void SampleClientSyncProvider_SchemaCreated(object sender, SchemaCreatedEventArgs e)
{
Console.WriteLine("Schema created for " + e.Table.TableName);
}
}
//Handle the statistics 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.
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 a Customer SyncGroup. This is not required
'for the single table we are synchronizing; it is typically
'used so that changes to multiple related tables are
'synchronized at the same time.
Dim customerSyncGroup As New SyncGroup("Customer")
'Add the Customer table: specify a synchronization direction of
'DownloadOnly and that an existing table should be dropped.
Dim customerSyncTable As New SyncTable("Customer")
customerSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable
customerSyncTable.SyncDirection = SyncDirection.DownloadOnly
customerSyncTable.SyncGroup = customerSyncGroup
Me.Configuration.SyncTables.Add(customerSyncTable)
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 command to retrieve a new anchor value from
'the server. In this case, we use a timestamp value
'that is retrieved and stored in the client database.
'During each synchronization, the new anchor value and
'the last anchor value from the previous synchronization
'are used: the set of changes between these upper and
'lower bounds is synchronized.
'
'SyncSession.SyncNewReceivedAnchor is a string constant;
'you could also use @sync_new_received_anchor directly in
'your queries.
Dim selectNewAnchorCommand As New SqlCommand()
Dim newAnchorVariable As String = "@" + SyncSession.SyncNewReceivedAnchor
With selectNewAnchorCommand
.CommandText = "SELECT " + newAnchorVariable + " = min_active_rowversion() - 1"
.Parameters.Add(newAnchorVariable, SqlDbType.Timestamp)
.Parameters(newAnchorVariable).Direction = ParameterDirection.Output
.Connection = serverConn
End With
Me.SelectNewAnchorCommand = selectNewAnchorCommand
'Create a SyncAdapter for the Customer table, and then define
'the commands to synchronize changes:
'* SelectIncrementalInsertsCommand, SelectIncrementalUpdatesCommand,
' and SelectIncrementalDeletesCommand are used to select changes
' from the server that the client provider then applies to the client.
'Create the SyncAdapter.
Dim customerSyncAdapter As New SyncAdapter("Customer")
'Select inserts from the server.
Dim customerIncrInserts As New SqlCommand()
With customerIncrInserts
.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer " _
& "WHERE (InsertTimestamp > @sync_last_received_anchor " _
& "AND InsertTimestamp <= @sync_new_received_anchor)"
.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp)
.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp)
.Connection = serverConn
End With
customerSyncAdapter.SelectIncrementalInsertsCommand = customerIncrInserts
'Select updates from the server.
Dim customerIncrUpdates As New SqlCommand()
With customerIncrUpdates
.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer " _
& "WHERE (UpdateTimestamp > @sync_last_received_anchor " _
& "AND UpdateTimestamp <= @sync_new_received_anchor " _
& "AND NOT (InsertTimestamp > @sync_last_received_anchor))"
.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp)
.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp)
.Connection = serverConn
End With
customerSyncAdapter.SelectIncrementalUpdatesCommand = customerIncrUpdates
'Select deletes from the server.
Dim customerIncrDeletes As New SqlCommand()
With customerIncrDeletes
.CommandText = _
"SELECT CustomerId, CustomerName, SalesPerson, CustomerType " _
& "FROM Sales.Customer_Tombstone " _
& "WHERE (@sync_initialized = 1 " _
& "AND DeleteTimestamp > @sync_last_received_anchor " _
& "AND DeleteTimestamp <= @sync_new_received_anchor)"
.Parameters.Add("@" + SyncSession.SyncInitialized, SqlDbType.Bit)
.Parameters.Add("@" + SyncSession.SyncLastReceivedAnchor, SqlDbType.Timestamp)
.Parameters.Add("@" + SyncSession.SyncNewReceivedAnchor, SqlDbType.Timestamp)
.Connection = serverConn
End With
customerSyncAdapter.SelectIncrementalDeletesCommand = customerIncrDeletes
'Add the SyncAdapter to the server synchronization provider.
Me.SyncAdapters.Add(customerSyncAdapter)
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 here we use this class to handle client
'provider events.
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
'Unlike Bidirectional and UploadOnly synchronization, we do
'not need to make schema changes for the Customer table. In
'those scenarios, we add defaults because inserts are made
'directly into the client database. We handle the events here
'so that we can write to the screen.
AddHandler Me.CreatingSchema, AddressOf SampleClientSyncProvider_CreatingSchema
AddHandler Me.SchemaCreated, AddressOf SampleClientSyncProvider_SchemaCreated
End Sub 'New
Private Sub SampleClientSyncProvider_CreatingSchema(ByVal sender As Object, ByVal e As CreatingSchemaEventArgs)
Console.Write("Creating schema for " + e.Table.TableName + " | ")
End Sub 'SampleClientSyncProvider_CreatingSchema
Private Sub SampleClientSyncProvider_SchemaCreated(ByVal sender As Object, ByVal e As SchemaCreatedEventArgs)
Console.WriteLine("Schema created for " + e.Table.TableName)
End Sub 'SampleClientSyncProvider_SchemaCreated
End Class 'SampleClientSyncProvider
'Handle the statistics 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