的SQL Server索引视图错误

我意识到这是一个很做作的例子，但我已经简化了完整版到这表明了问题的情况如下：的SQL Server索引视图错误

CREATE VIEW model.Appointments_Partition1 
WITH SCHEMABINDING AS 
    SELECT CONVERT(varchar(15), AppointmentId) as Id, 
     ap.AppTypeId as AppointmentTypeId, 
     ap.Duration as DurationMinutes, 
     ap.AppointmentId as EncounterId, 
     COUNT_BIG(*) as __count_big 
    FROM dbo.Appointments ap 
    JOIN dbo.PracticeCodeTable pct ON SUBSTRING(pct.Code, 1, 1) = ap.ScheduleStatus 
            AND pct.ReferenceType = 'AppointmentStatus' 
    WHERE ap.AppTime > 0 
GROUP BY CONVERT(varchar(15), AppointmentId), ap.AppTypeId, ap.Duration, ap.AppointmentId 

CREATE UNIQUE CLUSTERED INDEX [IX_Appointments_Partition1_Id] 
ON model.Appointments_Partition1 ([Id]);

我得到：

因为该视图的选择列表包含聚合函数或分组列的结果的表达式消息8668，级别16，状态0，第12行
无法对视图创建聚集索引“IX_Appointments_Partition1_Id“PracticeRepository.model.Appointments_Partition1”。考虑从选择列表中删除聚合函数或分组列的结果上的表达式。

我包括count_big ...那么为什么组是由一个问题？....我怎样才能解决这个错误？

来源

2011-11-18 Jeff

不知道我理解？ – Jeff