的SQL Server索引視圖錯誤

我意識到這是一個很做作的例子，但我已經簡化了完整版到這表明了問題的情況如下：的SQL Server索引視圖錯誤

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：

因爲該視圖的選擇列表包含聚合函數或分組列的結果的表達式消息8668，級別16，狀態0，第12行
無法對視圖創建聚集索引「IX_Appointments_Partition1_Id「PracticeRepository.model.Appointments_Partition1」。考慮從選擇列表中刪除聚合函數或分組列的結果上的表達式。

我包括count_big ...那麼爲什麼組是由一個問題？....我怎樣才能解決這個錯誤？

來源

2011-11-18 Jeff

不知道我理解？ – Jeff