Question

我将表数据加载到缓存中。并将其绑定到dropdown。但是如果在datatable中添加了任何新值，则该缓存应该无效并且新缓存应该得到create.I正在使用Asp.Net 3.5，linq to SQL < / p>

Folloing是我的.aspx代码

public List<Employee> GetEmployeeData()
    {
        //get from cache
        object obj = HttpRuntime.Cache.Get(Constants.Constants.cacheEmployee);
        if (obj != null)
        {
            return obj as List<Employee>;
        }
        else // get from database
        {

                using (TestdbEntities entities = new TestdbEntities(connectionString))
                {
                    try
                    {

                        IEnumerable<Employee> employee= entities.Employees.OrderBy(l => l.EmployeeName);

                        System.Web.Caching.SqlCacheDependencyAdmin.EnableNotifications(connectionString);

                        if (!System.Web.Caching.SqlCacheDependencyAdmin.GetTablesEnabledForNotifications(connectionString).Contains             ("master.Employee"))

                            System.Web.Caching.SqlCacheDependencyAdmin.EnableTableForNotifications(connectionString, "master.Employee");

                        System.Web.Caching.SqlCacheDependency sqldep = new System.Web.Caching.SqlCacheDependency(connectionString, "master.Employee"); ;

                        HttpRuntime.Cache.Insert(Constants.Constants.cacheEmployee, employee.ToList(), sqldep);

                        return employee.ToList();
                    }
                    catch (Exception ex)
                    {
                        throw ex;
                    }
                }
            }
        }

但我收到了以下错误

请确保数据库名称和表名称有效。表名必须符合SQL中常规标识符的格式。

请建议

Answer 1

另一个答案是正确的“。”在表名中是问题。由于某种原因，没有编写AspNet_SqlCacheRegisterTableStoredProcedure来处理不同的模式。

我必须把这个链接归功于这个问题： http://forums.asp.net/t/1249281.aspx?SQL+Cache+Dependency+with+custom+schema

然而，我想出了我自己重新编写下面的存储过程，这是一个更好的:)它有点干净，处理情况，即使[包括在名称中，并保持架构名称AspNet_SqlCacheTablesForChangeNotification表，以防您在两个不同的模式中具有相同的表名。

DECLARE @triggerName AS NVARCHAR(3000) 
DECLARE @fullTriggerName AS NVARCHAR(3000)
DECLARE @canonTableName NVARCHAR(3000) 
DECLARE @quotedTableName NVARCHAR(3000) 
DECLARE @schemaName NVARCHAR(3000)
DECLARE @schemaAndTableName NVARCHAR(3000)

--Replace these if they are in the param, we'll add them back later for the @canonTableName only
SET @tableName = REPLACE(REPLACE(@tableName, '[', ''), ']', '')

IF(CHARINDEX('.',@tableName) <> 0)
    BEGIN
        SET @schemaName = SUBSTRING(@tableName,0,CHARINDEX('.',@tableName))
        SET @tableName =  SUBSTRING(@tableName,CHARINDEX('.',@tableName) + 1,LEN(@tableName) - CHARINDEX('.',@tableName))
        SET @schemaAndTableName = @schemaName + '.' + @tableName
    END
ELSE
    BEGIN
        SET @schemaName = 'dbo' --If the param doesn't have a schema, use the default
        SET @schemaAndTableName = @tableName --If they didn't pass in the schema, we don't want it in the AspNet_SqlCacheTablesForChangeNotification table
    END

SET @triggerName = @tableName + '_AspNet_SqlCacheNotification_Trigger'
SET @fullTriggerName = '[' + @schemaName + '].[' + @triggerName + ']'
SET @canonTableName = '[' + @schemaName + '].[' + @tableName + ']'                  

/* First make sure the table exists */ 
IF (SELECT OBJECT_ID(@schemaAndTableName, 'U')) IS NULL
BEGIN
   RAISERROR ('00000001', 16, 1)
   RETURN
END

BEGIN TRAN
    /* Insert the value into the notification table */ 
    IF NOT EXISTS (SELECT tableName FROM dbo.AspNet_SqlCacheTablesForChangeNotification WITH (NOLOCK) WHERE tableName = @schemaAndTableName) 
     IF NOT EXISTS (SELECT tableName FROM dbo.AspNet_SqlCacheTablesForChangeNotification WITH (TABLOCKX) WHERE tableName = @schemaAndTableName) 
         INSERT  dbo.AspNet_SqlCacheTablesForChangeNotification 
         VALUES (@schemaAndTableName, GETDATE(), 0)

    /* Create the trigger */ 
    SET @quotedTableName = QUOTENAME(@schemaAndTableName, '''') 
    IF NOT EXISTS (SELECT name FROM sysobjects WITH (NOLOCK) WHERE name = @triggerName AND type = 'TR') 
     IF NOT EXISTS (SELECT name FROM sysobjects WITH (TABLOCKX) WHERE name = @triggerName AND type = 'TR') 
         EXEC('CREATE TRIGGER ' + @fullTriggerName + ' ON ' + @canonTableName +'
               FOR INSERT, UPDATE, DELETE AS BEGIN
               SET NOCOUNT ON
               EXEC dbo.AspNet_SqlCacheUpdateChangeIdStoredProcedure N' + @quotedTableName + '
               END
               ')
COMMIT TRAN

Answer 2

问题是表名.中的master.Employee。 EnableTableForNotifications方法调用数据库中的存储过程AspNet_SqlCacheRegisterTableStoredProcedure。在里面是对OBJECT_ID函数的调用，我认为这是将表名解析为master数据库中名为Employee的表。（当我第一次看到这个问题时，我的想法是一样的。）

如果您要使用表名中的下划线.替换_，那么您的代码将正确运行。

（您可能还希望在数据不在缓存中的情况下检查您的代码;数据可能由于多种原因从缓存中消失，但目前您的代码每次都会启用数据库以进行通知，无论它是否已经启用。Single Responsibility Principle适用于GetEmployeeData方法;它只应关注从缓存或数据库获取数据而不是设置缓存和通知，该代码应分解为单独的方法。）

Asp.Net中的Sql Cache依赖

2 个答案: