相关疑难解决方法(0)

我确实犯了一个愚蠢的错误,但我无法弄清楚:

在SQL Server 2005中,我尝试选择所有客户,除了那些在凌晨2点之前预订的客户.

当我运行此查询时:

SELECT idCustomer FROM reservations 
WHERE idCustomer NOT IN 
  (SELECT distinct idCustomer FROM reservations 
   WHERE DATEPART ( hour, insertDate) < 2)

我得到0结果.

但

SELECT idCustomer FROM reservations 

返回152.000结果和"NOT IN"部分:

SELECT distinct idCustomer FROM reservations 
WHERE DATEPART ( hour, insertDate) < 2

仅返回284行