我有这个SQL：

SELECT (Min(Time_In) & " to " & Max(Time_Out)) AS [Week Of],
 Round((Sum(DATEDIFF("n", Time_In, Time_Out))/Count(DATEDIFF("n", Time_In, Time_Out))),2) AS [Avg Min of Jog]
FROM SomeTable
WHERE len(Time_In) > 0 AND len(Time_Out) > 0 
AND #01/01/2012# <= Time_In AND #12/31/2012# >= Time_In
GROUP BY DatePart('ww',Time_In);

挑选出每周慢跑的平均时间。我也想有一个算很多次，每周慢跑如何，我正在尝试通过计算做jog_id在那里SomeTable可以有5个条目的一个jog_id。

我试过了：

SELECT (Min(Time_In) & " to " & Max(Time_Out)) AS [Week Of],
 Round((Sum(DATEDIFF("n", Time_In, Time_Out))/Count(DATEDIFF("n", Time_In, Time_Out))),2) AS [Avg Min of Jog],
 Count(distinct jog_id) AS [Num Jogs]
FROM SomeTable
WHERE len(Time_In) > 0 AND len(Time_Out) > 0 
AND #01/01/2012# <= Time_In AND #12/31/2012# >= Time_In
GROUP BY DatePart('ww',Time_In);

但这给了我 Syntax error (missing operator) in query expression 'Count(distinct jog_id)'.

我想念什么？