在没有主键的情况下定量删除数据！

整行语句：

select * from dbo.FreightRate where enabled=0 and createddate < (select max(createddate) as mx from (select top 100 createddate from dbo.FreightRate where order by createddate)a)

分解说明：

-- 按时间取前100条数据

１.select top 100 createddate from dbo.FreightRate where order by createddate

--取当前100条数据中最大的时间

2.select max(createddate) as mx from (select top 100 createddate from dbo.FreightRate where order by createddate)a

--再小于等于最大时间，注意一定要小于等于，才包括这个时间的全部数据

３.Delete from dbo.FreightRate where createddate <= (select max(createddate) as mx from (select top 100 createddate from dbo.FreightRate where order by createddate)a)

缺点：此方法是通知读取一定范围内的最大时间来确定数据集大小的。因此不一定总是前面子查询中的TOP100,实际会大于此数据集。本查询不适用于大量相同值的createddate表，否则就此方法定量也无从谈起。