Как создавать представления данных на клиенте

В этом разделе показано, как при помощи служб Sync Framework объединить две или более таблицы на сервере в одну таблицу в клиентской базе данных. В примерах, приведенных в этом разделе, обсуждаются следующие типы и события служб Sync Framework:

• DbServerSyncProvider

• SyncAdapter

• SyncTable

• SchemaCreated

Сведения о способах запуска образца кода см. в подразделе «Образцы приложений в разделах инструкций» раздела Программирование распространенных задач синхронизации клиента и сервера.

Пример

Следующие примеры кода демонстрируют синхронизацию таблиц Customer и CustomerContact в образце базы данных служб Sync Framework. В процессе начальной синхронизации производится выборка данных из двух таблиц с помощью команды добавочной вставки, их загрузка на сторону клиента и вставка в таблицу CustomerInfo. В процессе последующей синхронизации соответствующие изменения загружаются на клиент.

Ключевые элементы API-интерфейса

В этом разделе приведены примеры кода, иллюстрирующие использование ключевых элементов API-интерфейса для объединения таблиц. В следующих примерах кода описаны объекты SyncTable и SyncAdapter, в каждом из которых указана таблица CustomerInfo. Указание этого имени в обоих местах позволяет SyncAgent и поставщикам преобразовывать операции выборки из таблиц Customer и CustomerContact в операции вставки для таблицы CustomerInfo.

SyncTable customerInfoSyncTable = new SyncTable("CustomerInfo");
customerInfoSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable;
customerInfoSyncTable.SyncDirection = SyncDirection.DownloadOnly;
this.Configuration.SyncTables.Add(customerInfoSyncTable);

SyncAdapter customerInfoSyncAdapter = new SyncAdapter("CustomerInfo");

Dim customerInfoSyncTable As New SyncTable("CustomerInfo")
customerInfoSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable
customerInfoSyncTable.SyncDirection = SyncDirection.DownloadOnly
Me.Configuration.SyncTables.Add(customerInfoSyncTable)

Dim customerInfoSyncAdapter As New SyncAdapter("CustomerInfo")

Следующий пример кода содержит запрос для свойства SelectIncrementalInsertsCommand. Благодаря используемому в запросе соединению в процессе начальной синхронизации на клиент загружаются только те заказчики, для которых имеются контактные данные. В течение последующих сеансов синхронизации загружаются операции вставки в таблицу CustomerContact. Операции вставки в таблицу Customer загружаются только в том случае, если строка для заказчика вставляется также в таблицу CustomerContact. Обратите внимание, что список выбора содержит не все столбцы. Логика каждого из запросов, используемых в синхронизации, зависит от требований приложения. Например, можно произвести загрузку всех заказчиков, даже если они не имеют контактных данных.

SqlCommand customerInfoIncrementalInsertsCommand = new SqlCommand();
customerInfoIncrementalInsertsCommand.CommandType = CommandType.Text;
customerInfoIncrementalInsertsCommand.CommandText =
    "SELECT c.CustomerId, c.CustomerName, c.SalesPerson, cc.PhoneNumber, cc.PhoneType " +
    "FROM Sales.Customer c JOIN Sales.CustomerContact cc ON " +
    "c.CustomerId = cc.CustomerId " +
    "WHERE ((c.InsertTimestamp > @sync_last_received_anchor " +
    "AND c.InsertTimestamp <= @sync_new_received_anchor) OR " +
    "(cc.InsertTimestamp > @sync_last_received_anchor " +
    "AND cc.InsertTimestamp <= @sync_new_received_anchor))";
customerInfoIncrementalInsertsCommand.Parameters.Add("@sync_last_received_anchor", SqlDbType.Timestamp);
customerInfoIncrementalInsertsCommand.Parameters.Add("@sync_new_received_anchor", SqlDbType.Timestamp);
customerInfoIncrementalInsertsCommand.Connection = serverConn;
customerInfoSyncAdapter.SelectIncrementalInsertsCommand = customerInfoIncrementalInsertsCommand;

Dim customerInfoIncrementalInsertsCommand As New SqlCommand()
With customerInfoIncrementalInsertsCommand
    .CommandType = CommandType.Text
    .CommandText = _
        "SELECT c.CustomerId, c.CustomerName, c.SalesPerson, cc.PhoneNumber, cc.PhoneType " _
      & "FROM Sales.Customer c JOIN Sales.CustomerContact cc ON " _
      & "c.CustomerId = cc.CustomerId " _
      & "WHERE ((c.InsertTimestamp > @sync_last_received_anchor " _
      & "AND c.InsertTimestamp <= @sync_new_received_anchor) OR " _
      & "(cc.InsertTimestamp > @sync_last_received_anchor " _
      & "AND cc.InsertTimestamp <= @sync_new_received_anchor))"
    .Parameters.Add("@sync_last_received_anchor", SqlDbType.Timestamp)
    .Parameters.Add("@sync_new_received_anchor", SqlDbType.Timestamp)
    .Connection = serverConn
End With
customerInfoSyncAdapter.SelectIncrementalInsertsCommand = customerInfoIncrementalInsertsCommand

Следующий пример кода содержит запрос для свойства SelectIncrementalDeletesCommand. В запросе используются две инструкции SELECT и инструкция UNION, которая производит выборку удалений для таблиц Customer и CustomerContact. Первая инструкция SELECT соединяется с таблицей CustomerContact для получения столбца PhoneType. Этот столбец является частью составного ключа для таблицы CustomerInfo. Применяется следующая логика.

• Если заказчик был удален, то все строки для этого заказчика будут удалены на клиенте.

• Если были удалены контактные данные, то на клиенте будет удалена только эта строка.

• Если была удалена строка заказчика и его контактные данные, то будет загружено как минимум одно дополнительное удаление. Это не вызовет ошибок при применении изменений в клиентской базе данных.

SqlCommand customerInfoIncrementalDeletesCommand = new SqlCommand();
customerInfoIncrementalDeletesCommand.CommandType = CommandType.Text;
customerInfoIncrementalDeletesCommand.CommandText =
    "SELECT c.CustomerId, cc.PhoneType " +
    "FROM Sales.Customer_Tombstone c JOIN Sales.CustomerContact cc ON " +
    "c.CustomerId = cc.CustomerId " +
    "WHERE (@sync_initialized = 1 " +
    "AND (DeleteTimestamp > @sync_last_received_anchor " +
    "AND DeleteTimestamp <= @sync_new_received_anchor)) " +
    "UNION " +
    "SELECT CustomerId, PhoneType " +
    "FROM Sales.CustomerContact_Tombstone " +
    "WHERE (@sync_initialized = 1 " +
    "AND (DeleteTimestamp > @sync_last_received_anchor " +
    "AND DeleteTimestamp <= @sync_new_received_anchor))";
customerInfoIncrementalDeletesCommand.Parameters.Add("@sync_initialized", SqlDbType.Bit);
customerInfoIncrementalDeletesCommand.Parameters.Add("@sync_last_received_anchor", SqlDbType.Timestamp);
customerInfoIncrementalDeletesCommand.Parameters.Add("@sync_new_received_anchor", SqlDbType.Timestamp);
customerInfoIncrementalDeletesCommand.Connection = serverConn;
customerInfoSyncAdapter.SelectIncrementalDeletesCommand = customerInfoIncrementalDeletesCommand;

Dim customerInfoIncrementalDeletesCommand As New SqlCommand()
With customerInfoIncrementalDeletesCommand
    .CommandType = CommandType.Text
    .CommandText = _
        "SELECT c.CustomerId, cc.PhoneType " _
      & "FROM Sales.Customer_Tombstone c JOIN Sales.CustomerContact cc ON " _
      & "c.CustomerId = cc.CustomerId " _
      & "WHERE (@sync_initialized = 1 " _
      & "AND (DeleteTimestamp > @sync_last_received_anchor " _
      & "AND DeleteTimestamp <= @sync_new_received_anchor)) " _
      & "UNION " _
      & "SELECT CustomerId, PhoneType " _
      & "FROM Sales.CustomerContact_Tombstone " _
      & "WHERE (@sync_initialized = 1 " _
      & "AND (DeleteTimestamp > @sync_last_received_anchor " _
      & "AND DeleteTimestamp <= @sync_new_received_anchor))"
    .Parameters.Add("@sync_initialized", SqlDbType.Bit)
    .Parameters.Add("@sync_last_received_anchor", SqlDbType.Timestamp)
    .Parameters.Add("@sync_new_received_anchor", SqlDbType.Timestamp)
    .Connection = serverConn
End With
customerInfoSyncAdapter.SelectIncrementalDeletesCommand = customerInfoIncrementalDeletesCommand

В следующем примере кода создается составной первичный ключ для таблицы CustomerInfo. Он соответствует ключу для таблицы CustomerContact. Службы Sync Framework могут справиться по схеме таблиц на сервере, однако в данном случае указание ключа обязательно. Схему можно создать и вручную, как описано в разделе Как инициализировать клиентскую базу данных и работать со схемой таблицы.

string[] customerInfoPrimaryKey = new string[2];
customerInfoPrimaryKey[0] = "CustomerId";
customerInfoPrimaryKey[1] = "PhoneType";
e.Schema.Tables["CustomerInfo"].PrimaryKey = customerInfoPrimaryKey;

Dim customerInfoPrimaryKey(1) As String
customerInfoPrimaryKey(0) = "CustomerId"
customerInfoPrimaryKey(1) = "PhoneType"
e.Schema.Tables("CustomerInfo").PrimaryKey = customerInfoPrimaryKey

Полный пример кода

Приведенный ниже полный пример кода содержит все ранее описанные примеры и дополнительный код синхронизации. Для работы примеру необходим класс Utility, сведения о котором доступны в разделе Инструкции по классу Utility для поставщика базы данных. Обратите внимание, что вставка в таблицу Customer классом Utility при проведении последующих сеансов синхронизации загружена не будет, поскольку соответствующая строка отсутствует в таблице CustomerContact.

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");
            Utility.MakeDataChangesOnServer("CustomerContact");

            //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();

            //Add the Customer table: specify a synchronization direction of
            //DownloadOnly, and that an existing table should be dropped.
            SyncTable customerInfoSyncTable = new SyncTable("CustomerInfo");
            customerInfoSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable;
            customerInfoSyncTable.SyncDirection = SyncDirection.DownloadOnly;
            this.Configuration.SyncTables.Add(customerInfoSyncTable);

        }
    }

    //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 CustomerInfo table. The CustomerInfo 
            //table on the client is a combination of the Customer and CustomerContact
            //tables on the server. This table is download-only, as specified in 
            //SampleSyncAgent.
            SyncAdapter customerInfoSyncAdapter = new SyncAdapter("CustomerInfo");

            //Specify synchronization commands. The CustomerInfo table 
            //is download-only, so we do not define commands to apply changes to 
            //the server. Each command joins the base tables or tombstone tables
            //to select the appropriate incremental changes. For this application,
            //the logic is as follows:
            //* Select all inserts for customers that have contact information.
            //  This results in more than one row for a customer if that customer 
            //  has more than one phone number.
            //* Select all updates for customer and contact information that has 
            //  already been downloaded.
            //* Select all deletes for customer and contact information that has 
            //  already been downloaded. If a customer has been deleted, delete
            //  all of the rows for that customer. If a phone number has been
            //  deleted, delete only that row.

            //Select inserts.
            SqlCommand customerInfoIncrementalInsertsCommand = new SqlCommand();
            customerInfoIncrementalInsertsCommand.CommandType = CommandType.Text;
            customerInfoIncrementalInsertsCommand.CommandText =
                "SELECT c.CustomerId, c.CustomerName, c.SalesPerson, cc.PhoneNumber, cc.PhoneType " +
                "FROM Sales.Customer c JOIN Sales.CustomerContact cc ON " +
                "c.CustomerId = cc.CustomerId " +
                "WHERE ((c.InsertTimestamp > @sync_last_received_anchor " +
                "AND c.InsertTimestamp <= @sync_new_received_anchor) OR " +
                "(cc.InsertTimestamp > @sync_last_received_anchor " +
                "AND cc.InsertTimestamp <= @sync_new_received_anchor))";
            customerInfoIncrementalInsertsCommand.Parameters.Add("@sync_last_received_anchor", SqlDbType.Timestamp);
            customerInfoIncrementalInsertsCommand.Parameters.Add("@sync_new_received_anchor", SqlDbType.Timestamp);
            customerInfoIncrementalInsertsCommand.Connection = serverConn;
            customerInfoSyncAdapter.SelectIncrementalInsertsCommand = customerInfoIncrementalInsertsCommand;

            //Select updates.
            SqlCommand customerInfoIncrementalUpdatesCommand = new SqlCommand();
            customerInfoIncrementalUpdatesCommand.CommandType = CommandType.Text;
            customerInfoIncrementalUpdatesCommand.CommandText =
                "SELECT c.CustomerId, c.CustomerName, c.SalesPerson, cc.PhoneNumber, cc.PhoneType " +
                "FROM Sales.Customer c JOIN Sales.CustomerContact cc ON " +
                "c.CustomerId = cc.CustomerId " +
                "WHERE ((c.UpdateTimestamp > @sync_last_received_anchor " +
                "AND c.UpdateTimestamp <= @sync_new_received_anchor " +
                "AND c.InsertTimestamp <= @sync_last_received_anchor) " +
                "OR (cc.UpdateTimestamp > @sync_last_received_anchor " +
                "AND cc.UpdateTimestamp <= @sync_new_received_anchor " +
                "AND cc.InsertTimestamp <= @sync_last_received_anchor))";
            customerInfoIncrementalUpdatesCommand.Parameters.Add("@sync_last_received_anchor", SqlDbType.Timestamp);
            customerInfoIncrementalUpdatesCommand.Parameters.Add("@sync_new_received_anchor", SqlDbType.Timestamp);
            customerInfoIncrementalUpdatesCommand.Connection = serverConn;
            customerInfoSyncAdapter.SelectIncrementalUpdatesCommand = customerInfoIncrementalUpdatesCommand;

            //Select deletes.
            SqlCommand customerInfoIncrementalDeletesCommand = new SqlCommand();
            customerInfoIncrementalDeletesCommand.CommandType = CommandType.Text;
            customerInfoIncrementalDeletesCommand.CommandText =
                "SELECT c.CustomerId, cc.PhoneType " +
                "FROM Sales.Customer_Tombstone c JOIN Sales.CustomerContact cc ON " +
                "c.CustomerId = cc.CustomerId " +
                "WHERE (@sync_initialized = 1 " +
                "AND (DeleteTimestamp > @sync_last_received_anchor " +
                "AND DeleteTimestamp <= @sync_new_received_anchor)) " +
                "UNION " +
                "SELECT CustomerId, PhoneType " +
                "FROM Sales.CustomerContact_Tombstone " +
                "WHERE (@sync_initialized = 1 " +
                "AND (DeleteTimestamp > @sync_last_received_anchor " +
                "AND DeleteTimestamp <= @sync_new_received_anchor))";
            customerInfoIncrementalDeletesCommand.Parameters.Add("@sync_initialized", SqlDbType.Bit);
            customerInfoIncrementalDeletesCommand.Parameters.Add("@sync_last_received_anchor", SqlDbType.Timestamp);
            customerInfoIncrementalDeletesCommand.Parameters.Add("@sync_new_received_anchor", SqlDbType.Timestamp);
            customerInfoIncrementalDeletesCommand.Connection = serverConn;
            customerInfoSyncAdapter.SelectIncrementalDeletesCommand = customerInfoIncrementalDeletesCommand;

            //Add the SyncAdapter to the provider.
            this.SyncAdapters.Add(customerInfoSyncAdapter);

        }
    }

    //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;

            //Handle the two schema-related events.
            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 + " | ");

            //Create a compostite primary key for the CustomerInfo table.
            string[] customerInfoPrimaryKey = new string[2];
            customerInfoPrimaryKey[0] = "CustomerId";
            customerInfoPrimaryKey[1] = "PhoneType";
            e.Schema.Tables["CustomerInfo"].PrimaryKey = customerInfoPrimaryKey;
        }

        private void SampleClientSyncProvider_SchemaCreated(object sender, SchemaCreatedEventArgs e)
        {
            Console.WriteLine("Schema created for " + e.Table.TableName);
        }
    }

    //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")
        Utility.MakeDataChangesOnServer("CustomerContact")

        '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()

        'Add the Customer table: specify a synchronization direction of
        'DownloadOnly, and that an existing table should be dropped.
        Dim customerInfoSyncTable As New SyncTable("CustomerInfo")
        customerInfoSyncTable.CreationOption = TableCreationOption.DropExistingOrCreateNewTable
        customerInfoSyncTable.SyncDirection = SyncDirection.DownloadOnly
        Me.Configuration.SyncTables.Add(customerInfoSyncTable)

    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 CustomerInfo table. The CustomerInfo 
        'table on the client is a combination of the Customer and CustomerContact
        'tables on the server. This table is download-only, as specified in 
        'SampleSyncAgent.
        Dim customerInfoSyncAdapter As New SyncAdapter("CustomerInfo")

        'Specify synchronization commands. The CustomerInfo table 
        'is download-only, so we do not define commands to apply changes to 
        'the server. Each command joins the base tables or tombstone tables
        'to select the appropriate incremental changes. For this application,
        'the logic is as follows:
        '* Select all inserts for customers that have contact information.
        '  This results in more than one row for a customer if that customer 
        '  has more than one phone number.
        '* Select all updates for customer and contact information that has 
        '  already been downloaded.
        '* Select all deletes for customer and contact information that has 
        '  already been downloaded. If a customer has been deleted, delete
        '  all of the rows for that customer. If a phone number has been
        '  deleted, delete only that row.
        'Select inserts.
        Dim customerInfoIncrementalInsertsCommand As New SqlCommand()
        With customerInfoIncrementalInsertsCommand
            .CommandType = CommandType.Text
            .CommandText = _
                "SELECT c.CustomerId, c.CustomerName, c.SalesPerson, cc.PhoneNumber, cc.PhoneType " _
              & "FROM Sales.Customer c JOIN Sales.CustomerContact cc ON " _
              & "c.CustomerId = cc.CustomerId " _
              & "WHERE ((c.InsertTimestamp > @sync_last_received_anchor " _
              & "AND c.InsertTimestamp <= @sync_new_received_anchor) OR " _
              & "(cc.InsertTimestamp > @sync_last_received_anchor " _
              & "AND cc.InsertTimestamp <= @sync_new_received_anchor))"
            .Parameters.Add("@sync_last_received_anchor", SqlDbType.Timestamp)
            .Parameters.Add("@sync_new_received_anchor", SqlDbType.Timestamp)
            .Connection = serverConn
        End With
        customerInfoSyncAdapter.SelectIncrementalInsertsCommand = customerInfoIncrementalInsertsCommand

        'Select updates.
        Dim customerInfoIncrementalUpdatesCommand As New SqlCommand()
        With customerInfoIncrementalUpdatesCommand
            .CommandType = CommandType.Text
            .CommandText = _
                "SELECT c.CustomerId, c.CustomerName, c.SalesPerson, cc.PhoneNumber, cc.PhoneType " _
              & "FROM Sales.Customer c JOIN Sales.CustomerContact cc ON " _
              & "c.CustomerId = cc.CustomerId " _
              & "WHERE ((c.UpdateTimestamp > @sync_last_received_anchor " _
              & "AND c.UpdateTimestamp <= @sync_new_received_anchor " _
              & "AND c.InsertTimestamp <= @sync_last_received_anchor) " _
              & "OR (cc.UpdateTimestamp > @sync_last_received_anchor " _
              & "AND cc.UpdateTimestamp <= @sync_new_received_anchor " _
              & "AND cc.InsertTimestamp <= @sync_last_received_anchor))"
            .Parameters.Add("@sync_last_received_anchor", SqlDbType.Timestamp)
            .Parameters.Add("@sync_new_received_anchor", SqlDbType.Timestamp)
            .Connection = serverConn
        End With
        customerInfoSyncAdapter.SelectIncrementalUpdatesCommand = customerInfoIncrementalUpdatesCommand

        'Select deletes.
        Dim customerInfoIncrementalDeletesCommand As New SqlCommand()
        With customerInfoIncrementalDeletesCommand
            .CommandType = CommandType.Text
            .CommandText = _
                "SELECT c.CustomerId, cc.PhoneType " _
              & "FROM Sales.Customer_Tombstone c JOIN Sales.CustomerContact cc ON " _
              & "c.CustomerId = cc.CustomerId " _
              & "WHERE (@sync_initialized = 1 " _
              & "AND (DeleteTimestamp > @sync_last_received_anchor " _
              & "AND DeleteTimestamp <= @sync_new_received_anchor)) " _
              & "UNION " _
              & "SELECT CustomerId, PhoneType " _
              & "FROM Sales.CustomerContact_Tombstone " _
              & "WHERE (@sync_initialized = 1 " _
              & "AND (DeleteTimestamp > @sync_last_received_anchor " _
              & "AND DeleteTimestamp <= @sync_new_received_anchor))"
            .Parameters.Add("@sync_initialized", SqlDbType.Bit)
            .Parameters.Add("@sync_last_received_anchor", SqlDbType.Timestamp)
            .Parameters.Add("@sync_new_received_anchor", SqlDbType.Timestamp)
            .Connection = serverConn
        End With
        customerInfoSyncAdapter.SelectIncrementalDeletesCommand = customerInfoIncrementalDeletesCommand

        'Add the SyncAdapter to the provider.
        Me.SyncAdapters.Add(customerInfoSyncAdapter)

    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

        'Handle the two schema-related events.
        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 + " | ")

        'Create a compostite primary key for the CustomerInfo table.
        Dim customerInfoPrimaryKey(1) As String
        customerInfoPrimaryKey(0) = "CustomerId"
        customerInfoPrimaryKey(1) = "PhoneType"
        e.Schema.Tables("CustomerInfo").PrimaryKey = customerInfoPrimaryKey

    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 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

См. также

Другие ресурсы

Программирование распространенных задач синхронизации клиента и сервера