SqlCacheDependency 建構函式

public:
 SqlCacheDependency(System::Data::SqlClient::SqlCommand ^ sqlCmd);

public SqlCacheDependency(System.Data.SqlClient.SqlCommand sqlCmd);

new System.Web.Caching.SqlCacheDependency : System.Data.SqlClient.SqlCommand -> System.Web.Caching.SqlCacheDependency

Public Sub New (sqlCmd As SqlCommand)

參數

例外狀況

備註

此建構器用於建立利用 SQL Server 2005 產品查詢通知功能SqlCacheDependency物件。

與參數 sqlCmd 相關聯的 SQL 語句必須包含以下內容：

• 完全合格的表格名稱，包括桌主姓名。 例如，若要參考由資料庫擁有者擁有的名為 Customers 的資料表，SQL 陳述必須參考 dbo.customers。

• Select 語句中明確的欄位名稱。 你不能用星號（*）萬用字元來選擇表格中的所有欄位。 例如，你 select * from dbo.customers必須使用 select name, address, city, state from dbo.customers。

此建構器無法用來將 SqlCommand 實例與頁面上 SQL Server 2005 查詢通知及頁面層級輸出快取的 SqlCacheDependency 實例關聯起來。

另請參閱

• SqlCacheDependency(String, String)

public:
 SqlCacheDependency(System::String ^ databaseEntryName, System::String ^ tableName);

public SqlCacheDependency(string databaseEntryName, string tableName);

new System.Web.Caching.SqlCacheDependency : string * string -> System.Web.Caching.SqlCacheDependency

Public Sub New (databaseEntryName As String, tableName As String)

參數

例外狀況

範例

以下程式碼範例使用此建構子建立一個 SqlCacheDependency 類別實例，該類別與一個名為 Categories 的資料庫資料表相關聯，該資料表位於一個名為 Northwind 的SQL Server資料庫中。

public void Page_Load(object Src, EventArgs E) 
{ 
    // Declare the SqlCacheDependency instance, SqlDep. 
    SqlCacheDependency SqlDep = null; 
    
    // Check the Cache for the SqlSource key. 
    // If it isn't there, create it with a dependency 
    // on a SQL Server table using the SqlCacheDependency class. 
    if (Cache["SqlSource"] == null) { 
        
        // Because of possible exceptions thrown when this 
        // code runs, use Try...Catch...Finally syntax. 
        try { 
            // Instantiate SqlDep using the SqlCacheDependency constructor. 
            SqlDep = new SqlCacheDependency("Northwind", "Categories"); 
        } 
        
        // Handle the DatabaseNotEnabledForNotificationException with 
        // a call to the SqlCacheDependencyAdmin.EnableNotifications method. 
        catch (DatabaseNotEnabledForNotificationException exDBDis) { 
            try { 
                SqlCacheDependencyAdmin.EnableNotifications("Northwind"); 
            } 
            
            // If the database does not have permissions set for creating tables, 
            // the UnauthorizedAccessException is thrown. Handle it by redirecting 
            // to an error page. 
            catch (UnauthorizedAccessException exPerm) { 
                Response.Redirect(".\\ErrorPage.htm"); 
            } 
        } 
        
        // Handle the TableNotEnabledForNotificationException with 
        // a call to the SqlCacheDependencyAdmin.EnableTableForNotifications method. 
        catch (TableNotEnabledForNotificationException exTabDis) { 
            try { 
                SqlCacheDependencyAdmin.EnableTableForNotifications("Northwind", "Categories"); 
            } 
            
            // If a SqlException is thrown, redirect to an error page. 
            catch (SqlException exc) { 
                Response.Redirect(".\\ErrorPage.htm"); 
            } 
        } 
        
        // If all the other code is successful, add MySource to the Cache 
        // with a dependency on SqlDep. If the Categories table changes, 
        // MySource will be removed from the Cache. Then generate a message 
        // that the data is newly created and added to the cache. 
        finally { 
            Cache.Insert("SqlSource", Source1, SqlDep); 
            CacheMsg.Text = "The data object was created explicitly."; 
            
        } 
    } 
    
    else { 
        CacheMsg.Text = "The data was retrieved from the Cache."; 
    } 
} 

Sub Page_Load(Src As Object, E As EventArgs)
   ' Declare the SqlCacheDependency instance, SqlDep.
   Dim SqlDep As SqlCacheDependency

   ' Check the Cache for the SqlSource key.
   ' If it isn't there, create it with a dependency
   ' on a SQL Server table using the SqlCacheDependency class.
   If Cache("SqlSource") Is Nothing

      ' Because of possible exceptions thrown when this
      ' code runs, use Try...Catch...Finally syntax.
      Try
         ' Instantiate SqlDep using the SqlCacheDependency constructor.
         SqlDep = New SqlCacheDependency("Northwind", "Categories")

      ' Handle the DatabaseNotEnabledForNotificationException with
      ' a call to the SqlCacheDependencyAdmin.EnableNotifications method.
      Catch exDBDis As DatabaseNotEnabledForNotificationException
         Try
            SqlCacheDependencyAdmin.EnableNotifications("Northwind")

         ' If the database does not have permissions set for creating tables,
         ' the UnauthorizedAccessException is thrown. Handle it by redirecting
         ' to an error page.
         Catch exPerm As UnauthorizedAccessException
             Response.Redirect(".\ErrorPage.htm")
         End Try

      ' Handle the TableNotEnabledForNotificationException with
            ' a call to the SqlCacheDependencyAdmin.EnableTableForNotifications method.
      Catch exTabDis As TableNotEnabledForNotificationException
         Try
            SqlCacheDependencyAdmin.EnableTableForNotifications( _
             "Northwind", "Categories")

         ' If a SqlException is thrown, redirect to an error page.
         Catch exc As SqlException
             Response.Redirect(".\ErrorPage.htm")
         End Try

      ' If all the other code is successful, add MySource to the Cache
      ' with a dependency on SqlDep. If the Categories table changes,
      ' MySource will be removed from the Cache. Then generate a message
            ' that the data is newly created and added to the cache.
      Finally
         Cache.Insert("SqlSource", Source1, SqlDep)
            CacheMsg.Text = "The data object was created explicitly."

      End Try

    Else
       CacheMsg.Text = "The data was retrieved from the Cache."
    End If
End Sub

備註

此建構器用於為 SQL Server 7.0 與 SQL Server 2000 產品建立 SqlCacheDependency 物件。

傳遞給參數 database 的資料庫名稱必須在應用程式的 Web.config 檔案中定義。 例如，以下的 Web.config 檔案定義了一個名為 pubs 的資料庫，用於變更 SqlCacheDependency 通知。

<configuration>
  <connectionStrings>
    <add name="Pubs" connectionString="Data Source=(local); Initial Catalog=pubs; Integrated Security=true"; providerName="System.Data.SqlClient" />
  </connectionStrings>
  <system.web>
    <caching>
      <sqlCacheDependency enabled = "true" pollTime = "60000" >
        <databases>
          <add name="pubs"
            connectionStringName="pubs"
            pollTime="9000000"
            />
        </databases>
      </sqlCacheDependency>
    </caching>
  </system.web>
</configuration>

使用此構造子時，通常會拋出兩個例外： DatabaseNotEnabledForNotificationException 和 TableNotEnabledForNotificationException。 如果拋出 a DatabaseNotEnabledForNotificationException ，你可以用例外處理程式碼呼叫該 SqlCacheDependencyAdmin.EnableNotifications 方法，或使用 aspnet_regsql.exe 命令列工具設定資料庫以接收通知。 如果拋出 a TableNotEnabledForNotificationException ，你可以呼叫該 SqlCacheDependencyAdmin.EnableTableForNotifications 方法或 use aspnet_regsql.exe 來設定通知表。

另請參閱

• SqlCacheDependency(SqlCommand)