Question

我有一个包含事件的表，我需要找到重复的事件。问题是彼此相隔1秒发生的事件被认为是重复的。所以如果我的表有这些值

id | var1 | var2 | var3 | date
1  | 1    | 2    | 3    | 2001-01-01 01:01:01.456
2  | 1    | 2    | 3    | 2001-01-01 01:01:02.234
3  | 1    | 2    | 3    | 2001-01-01 01:01:04.789

记录1和2被认为是重复的，因为它们在1秒内，但3不是因为它在2之后超过1秒。

有没有办法编写只选择一系列重复项中第一条记录的查询？

编辑：可能还有一些不需要捕获的重复行。 Id是表的主键，不在匹配条件中使用;它只是为了澄清。

Answer 1

Lag is one possible solution, something like this:

select * from (
select *, lag(date,1) over(order by date) previoustime from yourtable
) x
where datediff(second,previoustime,date)<1

Answer 2

这是一种看起来应该适合你的方式。

一些假设：

我假设复制是一个不包括ID的实际行复制，基于您提供的1秒子句。如果不是这种情况......通过部分row_number()窗口函数删除分区，它将改变行为
这会删除递归重复项。也就是说，如果3,4或甚至15行彼此在一秒内，则保持为1.
无论第一行还是最后一行是重复的

这是代码。取消注释表中的两行以查看更改

declare @table table(id int, var1 int, var2 int, var3 int, date datetime2)
insert into @table
values
--(0,1,2,3,'2001-01-01 00:01:01.456'), 

(1,1,2,3,'2001-01-01 01:01:01.456'), --dupe of 1/2/3
(2,1,2,3,'2001-01-01 01:01:02.214'), --dupe of 1/2/3
(3,1,2,3,'2001-01-01 01:01:02.234'), --dupe of 1/2/3
(4,1,2,3,'2001-01-01 01:01:02.244'), --dupe of 1/2/3

(5,1,2,3,'2001-01-01 01:01:04.789'), --dupe of 4/5
(6,1,2,3,'2001-01-01 01:01:04.989'), --dupe of 4/5

--(7,1,2,3,'2001-01-01 01:01:06.789'), --dupe of 6/7
(8,1,2,3,'2001-01-01 01:01:06.799') --dupe of 6/7

--apply the sequence
;with cte as(
select 
    *,
    ROW_NUMBER() over (partition by var1, var2, var3 order by date) as RN  --just in case... change this to just order by id, date if need be and remove the partition
from 
    @table),

--get first / most of the batch to remove
cte2 as(
select
    c1.*
    ,c2.RN as RowsToRemove
from cte c1
left join
    cte c2 on c1.RN < c2.rn  and 
    datediff(second,c1.date,c2.date) < 1),


--remove the rows identified in the above cte
cte3 as(
select distinct
    ID, 
    var1,
    var2,
    var3,
    date,
    RN
from cte2
where 
    RN not in (select distinct isnull(RowsToRemove,0) from cte2)),

--add another sequence. This is necessary for first/last row check for duplicate
cte4 as(
select
    f.*,
    row_number() over (partition by var1, var2, var3 order by date) RN2
from 
    cte3 f)

--return the results
select 
    f.ID, 
    f.var1,
    f.var2,
    f.var3,
    f.date
from 
    cte4 f
left join
    cte4 d on d.RN = f.RN - 1
where isnull(datediff(second,d.date,f.date),500) > 1

<强>返回

+----+------+------+------+-----------------------------+
| ID | var1 | var2 | var3 |            date             |
+----+------+------+------+-----------------------------+
|  1 |    1 |    2 |    3 | 2001-01-01 01:01:01.4560000 |
|  5 |    1 |    2 |    3 | 2001-01-01 01:01:04.7890000 |
|  8 |    1 |    2 |    3 | 2001-01-01 01:01:06.7990000 |
+----+------+------+------+-----------------------------+

Answer 3

    select T1.date,... from MyTable T1
left outer join MyTable T2 on cast(T1.date as date) = cast(T2.date as date) and 
datediff(second,T1.date,T2.date)<=1
group by cast(T1.date as date)

Sql Server：根据其他记录的日期按日期对记录进行分组的任何方法吗？

3 个答案: