Question

如何从SQL Server中除最大日期以外的表中删除数据？我试过像这样的条件 (HAVING MAX(dated) != date)但它不起作用。

假设我们有一个包含多列的表。第一个是手机号码，第二个是日期，剩下的是 bla bla 。现在，我想删除那些没有MAX日期的手机号码，重复使用不同日期的手机号码。在其他作品中，我想只保留那些具有MAX日期的数字并删除重复。

请帮助..

Answer 1

一种方法是在delete语句中使用内部联接到派生表：

创建并填充样本表（请在下一个问题中保存此步骤）

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删除声明

DECLARE @T as TABLE 
(
    Mobile char(1),
    Dated date
)

INSERT INTO @T VALUES
('A', GETDATE()),
('A', GETDATE() - 1),
('A', GETDATE() + 2),
('B', GETDATE() - 1),
('B', GETDATE() + 3),
('B', GETDATE())

Answer 2

借助OUTER APPLY的另一种方式：

DELETE FROM y
FROM YourTable y
OUTER APPLY (
    SELECT top 1 * 
    FROM YourTable
    WHERE y.ID = ID
    ORDER BY dated DESC
) as y2
WHERE CAST(y.dated as date) < CAST(y2.dated as date)

Answer 3

使用此查询删除最大日期以外的记录

DECLARE @maxDate DATE

SELECT TOP 1 @maxDate = CAST(CreatedDate AS DATE)
FROM <Table1>
ORDER BY CreatedDate DESC

DELETE
FROM <Table1>
WHERE CAST(CreatedDate AS DATE) != @maxDate

如果此查询符合您的要求，请将此标记为答案。

删除与MAX日期相关的重复

3 个答案: