Question

如何从Microsoft SQL Server表中删除所有重复的月份？

例如，使用以下语法创建：

SELECT * FROM Cash WHERE Id = '2' AND TransactionDate between '2014/07/01' AND '2015/02/28'

，查询结果为：

+----+-------------------------+
|Id  | TransactionDate         |
+----+-------------------------+
| 2  | 2014-07-22 00:00:00.000 |
| 2  | 2014-08-09 00:00:00.000 |
| 2  | 2014-08-25 00:00:00.000 |
| 2  | 2014-08-29 00:00:00.000 |
| 2  | 2015-01-27 00:00:00.000 |
| 2  | 2015-01-28 00:00:00.000 |
+----+-------------------------+

我如何删除重复月份，每个月只返回1个月的任何1个值，如下结果：

+----+-------------------------+
|Id  | TransactionDate         |
+----+-------------------------+
| 2  | 2014-07-22 00:00:00.000 |
| 2  | 2014-08-09 00:00:00.000 |
| 2  | 2015-01-27 00:00:00.000 |
+----+-------------------------+

Answer 1

您可以在ROW_NUMBER的帮助下完成。

这将告诉您要保留哪些行

SELECT id,transactionDate, ROW_NUMBER() OVER ( PARTITION BY YEAR(TransactionDate ),MONTH(TransactionDate ) ORDER BY TransactionDate ) firstTrans
FROM Cash 
WHERE Id = '2' AND 
TransactionDate between '2014/07/01' AND '2015/02/28'

您可以使用CTE删除其他行。

with myCTE (id,transactionDate, firstTrans) AS (
 SELECT id,transactionDate, ROW_NUMBER() OVER ( PARTITION BY YEAR(TransactionDate ),MONTH(TransactionDate ) ORDER BY TransactionDate ) firstTrans
    FROM Cash 
    WHERE Id = '2' AND 
    TransactionDate between '2014/07/01' AND '2015/02/28'
)
delete from myCTE where firstTrans <> 1

每年每个月只会保留一笔交易。

修改

按row_number过滤，只返回您想要的行

select id, transactionDate from (SELECT id,transactionDate, ROW_NUMBER() OVER ( PARTITION BY YEAR(TransactionDate ),MONTH(TransactionDate ) ORDER BY TransactionDate ) firstTrans FROM Cash WHERE Id = '2' AND TransactionDate between '2014/07/01' AND '2015/02/28') where firstTrans = 1

Answer 2

仅选择每月的第一行

SELECT *
FROM Cash c
WHERE c.Id = '2' 
AND c.TransactionDate between '2014/07/01' AND '2015/02/28'
AND NOT EXISTS ( SELECT 'a'
                   FROM Cash c2
                   WHERE c2.Id = c.Id
                   AND YEAR(c2.TransactionDate) * 100 + MONTH(c2.TransactionDate) = YEAR(c.TransactionDate) * 100 + MONTH(c.TransactionDate)
                   AND c2.TransactionDate < c.TransactionDate
               )

Answer 3

当您运行此查询时，您将获得每年每月最高的ID。

SELECT MAX(<IdColumn>) AS Id, YEAR(<DateColumn>) AS YE, MONTH(<DateColumn>) AS MO FROM <YourTable>
GROUP BY YEAR(<DateColumn>), MONTH(<DateColumn>)

例如，如果需要，您可以延迟删除其ID不在此查询中的行。

删除重复的行查询结果，除了Microsoft SQL Server中的一个？

3 个答案: