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Drowning in a selective DELETE statement in one table in t-SQL

Let's say I have a table like this (SQL Server 2008):

CREATE TABLE tbl (ID INT, dtIn DATETIME2, dtOut DATETIME2, Type INT)

INSERT tbl VALUES
(1, '05:00', '6:00', 1),  -- will be removed
(2, '05:00', '7:00', 1),  -- will be removed
(3, '05:01', '8:00', 1),
(4, '05:00', '8:00', 1),
(5, '05:00', '6:00', 2),  -- will be removed
(6, '05:00', '7:00', 2),
(7, '05:00', '7:00', 3),
(8, '04:00', '7:00', 3)

I need to delete all records of the same "type" (if 2 or more are found) with the same "dtIn" for my "type", except for one with the largest "dtOut". In other words, the above table should lead to the following:

(3, '05:01', '8:00', 1),   -- no matching 'dtIn' for 'type' = 1
(4, '05:00', '8:00', 1),   -- largest 'dtOut' for 'type' = 1
(6, '05:00', '7:00', 2),   -- largest 'dtOut' for 'type' = 2
(7, '05:00', '7:00', 3),   -- no matching 'dtIn' for 'type' = 3
(8, '04:00', '7:00', 3)    -- no matching 'dtIn' for 'type' = 4

How do you even select multiple rows with the same type from the same table. You cannot do select * from tbl where type = type .... In any case, I would appreciate help in this ...

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5 answers

Here is one way to select the rows you want to delete:

SELECT *
FROM tbl T1
WHERE EXISTS
(
    SELECT *
    FROM tbl T2
    WHERE T1.Type = T2.Type
    AND T1.dtIn = T2.dtIn
    AND (
            T1.dtOut < T2.dtOut
            OR (T1.dtOut = T2.dtOut AND T1.id < T2.id)
        )
)

. SELECT * DELETE T1. , , , , , delete.

, : sqlfiddle

ROW_NUMBER:

;WITH T1 AS (
    SELECT id, ROW_NUMBER() OVER (PARTITION BY Type, dtIn
                                  ORDER BY dtOut DESC, ID DESC) AS rn
    FROM tbl
)
SELECT * FROM tbl
WHERE id IN
(
    SELECT id
    FROM T1
    WHERE rn > 1
)

, : sqlfiddle

+7

(+ ), .

;with my_cte(ID)
as
(
  SELECT T1.ID
  FROM 
      tbl T1
      JOIN tbl T2 on
        T1.Type = T2.Type
        AND T1.dtIn = T2.dtIn
        AND T1.dtOut < T2.dtOut
  )
select *
from tbl t
where not exists 
              (
              select 1 
              from my_cte c 
              where t.ID = c.ID
              )
+1

, . :

DELETE X
FROM
   (SELECT Row_Number() OVER (PARTITION BY Type, dtIn ORDER BY dtOut DESC) Item, *
   FROM #tbl) X
WHERE Item > 1

, , .

DELETE T
FROM #tbl T
   CROSS APPLY (
      SELECT TOP 1 *
      FROM #tbl T2
      WHERE
         T.dtIn = T2.dtIn
         AND T.Type = T2.Type
      ORDER BY T2.dtOut DESC, T2.ID DESC
   ) X
WHERE T.ID < X.ID


DELETE T
FROM #tbl T
   INNER JOIN #tbl T2
      ON T.dtIn = T2.dtIn
      AND T.Type = T2.Type
      AND (
         T.dtOut < T2.dtOut
         OR (T.tdOut = T2.dtOut AND T.ID > T2.ID)
      )

( ID), :

DELETE T
FROM #tbl T
WHERE EXISTS (
   SELECT * FROM #tbl T2
   WHERE
      T.dtIn = T2.dtIn
      AND T.Type = T2.Type
      AND T.dtOut < T2.dtOut
)


DELETE T
FROM #tbl T
   INNER JOIN #tbl T2
      ON T.dtIn = T2.dtIn
      AND T.Type = T2.Type
      AND T.dtOut < T2.dtOut
+1

Mine is slightly different from @Mark, but I believe that it should get the same results (just because I assume it idis unique):

DELETE a
FROM dbo.tbl a
WHERE id <> (
    SELECT MAX(id)
    from dbo.tbl b
    WHERE a.type = b.type
      AND a.dtIn = b.dtIn
)
0
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DECLARE @Table TABLE     
(  
ID INT,  
newno int  
)   

insert @table  
SELECT T1.ID,   
ROW_NUMBER() OVER (PARTITION BY Type, dtIn
                              ORDER BY dtOut DESC, ID DESC) AS newno  
 FROM tbl T1      

 select *  
from tbl t
where t.ID IN
             (
              select ID from @Table where newno > 1
              )
0
source

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