根据条件删除重复项

Question

对于下面给定的数据集，我想删除时间戳较晚的行。

**37C1Z2990E5E0 (TRXID) should be UNIQUE** in the below dataSet

    JKLAMMSDF123    20141112    20141117    5000.0  P   1.22    RT101018    *2014-11-12 10:10:26*   37C1Z2990E5E0   101018
    JKLAMMSDF123    20141110    20141114    5000.0  P   1.22    RT161002    *2014-11-12 10:11:33*   37C1Z2990E5E0   161002

-- More rows

Answer 1

Select 时间戳列的最小值并按所有其他列分组。

SELECT MIN(TIMESTAMP), C1, C2, C3...
FROM YOUR_TABLE
GROUP BY C1, C2, C3..

Answer 2

试试这个：

;WITH DATA AS
(
    SELECT TRXID, MAX(YourTimestampColumn) AS TS
    FROM YourTable
    GROUP BY TRXID
    HAVING COUNT(*) > 1
)
DELETE T
FROM YourTable AS T
INNER JOIN DATA AS D
    ON T.TRXID = D.TRXID
   AND T.YourTimestampColumn = D.TS;

Answer 3

我将使用 window function 加 CTE 来完成此操作。

要在删除重复项后检查结果，请使用此选项。

;WITH DATA
     AS (SELECT *,
                Row_number()OVER(partition BY TRXID ORDER BY YourTimestampColumn) rn
         FROM   YourTable)
select * 
FROM data
WHERE  rn = 1

到 delete 重复项使用此。

;WITH DATA
     AS (SELECT *,
                Row_number()OVER(partition BY TRXID ORDER BY YourTimestampColumn) rn
         FROM   YourTable)
DELETE FROM data
WHERE  rn > 1

即使您重复多次相同的 TRXID

，这仍然有效

根据条件删除重复项

Remove duplicates based on a condition

sql

database

sql-server