Sql 逻辑返回被删除的行，而不是保留的行。 ID Date Value 1 2015-01-01 1 2 2015-01-02 1 <redundant 3 2015-01-03 2 4

逻辑返回被删除的行，而不是保留的行。

ID    Date        Value  
1     2015-01-01  1  
2     2015-01-02  1 <redundant  
3     2015-01-03  2  
4     2015-01-05  2 <redundant  
5     2015-01-06  1  
6     2015-01-08  1 <redundant  
7     2015-01-09  1 <redundant  
8     2015-01-10  2  
9     2015-01-11  3  
10    2015-01-12  3 <redundant  

SELECT ID, Date, Value,
RANK() over(partition by Value order by Date ASC) Rank,
FROM DataLogging 
ORDER BY Date ASC 

ID    Date        Value  Rank   (Rank)
1     2015-01-01  1      1      (1)
2     2015-01-02  1      2      (2)
3     2015-01-03  2      1      (1)
4     2015-01-05  2      2      (2)
5     2015-01-06  1      3      (1)
6     2015-01-08  1      4      (2)
7     2015-01-09  1      5      (3)
8     2015-01-10  2      3      (1)
9     2015-01-11  3      1      (1)
10    2015-01-12  3      2      (2)

select * 
from  ( select ID, Date, Value, lag(Value, 1, 0) over (order by ID) as ValueLag 
        from table ) tt
where ValueLag is null or ValueLag <> Value  

declare @tt table  (id tinyint, val tinyint);
insert into @tt values 
( 1, 1),
( 2, 1),
( 3, 2),
( 4, 2),
( 5, 1),
( 6, 1),
( 7, 1),
( 8, 2),
( 9, 3),
(10, 3);

select id, val, LAG(val) over (order by id) as lagVal
from @tt;

-- find the good
select id, val 
from ( select id, val, LAG(val) over (order by id) as lagVal
       from @tt 
     ) tt
where  lagVal is null or lagVal <> val 

-- select the bad 
select tt.id, tt.val 
  from @tt tt
  left join ( select id, val 
                from ( select id, val, LAG(val) over (order by id) as lagVal
                         from @tt 
                     ) ttt
               where   ttt.lagVal is null or ttt.lagVal <> ttt.val 
            ) tttt 
    on tttt.id = tt.id 
 where tttt.id is null

WITH CTE AS
(
    SELECT  *, 
            ROW_NUMBER() OVER(ORDER BY [Date]) RN1,
            ROW_NUMBER() OVER(PARTITION BY Value ORDER BY [Date]) RN2
    FROM dbo.YourTable
), CTE2 AS
(
    SELECT *, ROW_NUMBER() OVER(PARTITION BY Value, RN1 - RN2 ORDER BY [Date]) N
    FROM CTE
)
SELECT *
FROM CTE2
ORDER BY ID;

╔════╦════════════╦═══════╦═════╦═════╦═══╗
║ ID ║    Date    ║ Value ║ RN1 ║ RN2 ║ N ║
╠════╬════════════╬═══════╬═════╬═════╬═══╣
║  1 ║ 2015-01-01 ║     1 ║   1 ║   1 ║ 1 ║
║  2 ║ 2015-01-02 ║     1 ║   2 ║   2 ║ 2 ║
║  3 ║ 2015-01-03 ║     2 ║   3 ║   1 ║ 1 ║
║  4 ║ 2015-01-05 ║     2 ║   4 ║   2 ║ 2 ║
║  5 ║ 2015-01-06 ║     1 ║   5 ║   3 ║ 1 ║
║  6 ║ 2015-01-08 ║     1 ║   6 ║   4 ║ 2 ║
║  7 ║ 2015-01-09 ║     1 ║   7 ║   5 ║ 3 ║
║  8 ║ 2015-01-10 ║     2 ║   8 ║   3 ║ 1 ║
║  9 ║ 2015-01-11 ║     3 ║   9 ║   1 ║ 1 ║
║ 10 ║ 2015-01-12 ║     3 ║  10 ║   2 ║ 2 ║
╚════╩════════════╩═══════╩═════╩═════╩═══╝

DELETE FROM CTE2
WHERE N > 1;

with todelete as (
      select t.*, lag(value) over (order by date) as prev_value
      from t
     )
delete from todelete
    where value = prev_value;

with todelete as (
      select t.*, lag(value) over (order by date) as prev_value
      from t
     )
select *
from todelete
where value <> prev_value or prev_value is null;

;WITH Ordered AS
(
    SELECT ROW_NUMBER() OVER (ORDER BY [Date]) AS [Row], *
    FROM DataLogging
),
Final AS
(
    SELECT
        o1.*, NULLIF(o1.Value - ISNULL(o2.Value, o1.Value - 1), 0) [Change]
    FROM
        Ordered o1
        LEFT JOIN Ordered o2 ON
            o1.[Row] = o2.[Row] + 1
)
SELECT * FROM Final

DELETE FROM DataLogging where Change IS NULL