Sql server 2005 sqlserver2005中的Union

以下是我的疑问

 Select vehicleID from trip where (StartingDate between ''+ convert(varchar(10), @StartDate,111) +'' and ''+ convert(varchar(10), @EndDate,111)+'')
or (enddate between ''+ convert(varchar(10), @StartDate,111) +'' and ''+ convert(varchar(10), @EndDate,111)+'')
or(StartingDate <= @StartDate and enddate >= @EndDate)
UNION
Select vehicleID from VehicleMaintenance where (FromDate between ''+ convert(varchar(10), @StartDate,111) +'' and ''+ convert(varchar(10), @EndDate,111)+'')
or (todate between ''+ convert(varchar(10), @StartDate,111) +'' and ''+ convert(varchar(10), @EndDate,111)+'')
or (FromDate <= @StartDate and todate >= @EndDate)
) as vehicle

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如何从上述查询结果中选择不同的vehicleId…

请注意，UNION将删除重复项，而UNION ALL不会，因此您应该已经拥有唯一的车辆ID

Hmmm。。。使用union语句应该只返回不同的记录，是否缺少查询的一部分？