Question

我想在SQL Server中删除我的重复值。所以我找到了一个可以找到它们的查询，如何将delete语句附加到此查询中以删除它们？

(SELECT
    DocumentNumber, LineNumber, SheetNumber, Unit, COUNT(*)
FROM
    Lines
GROUP BY
    DocumentNumber, LineNumber, SheetNumber, Unit
HAVING 
    COUNT(*) > 1)

Answer 1

我会使用CTE和排名函数ROW_NUMBER：

;WITH CTE AS
(
   SELECT Id, DocumentNumber, LineNumber, SheetNumber, Unit,
          RN = ROW_NUMBER() OVER (PARTITION BY DocumentNumber, LineNumber, SheetNumber, Unit 
                                  ORDER BY Id DESC) -- keeps the newest Id-row
   FROM dbo.Lines
)
DELETE FROM CTE WHERE RN > 1

非常有益，它更易于阅读和维护，并且很容易将其更改为SELECT * FROM CTE以查看您要删除的内容。

修改Order By部分以实现自定义逻辑，以保留要保留的行以及要删除的行。它可以包含多个列（ASC或DESC）甚至条件语句（f.e. with CASE）。

Answer 2

以下是一些方法：

$key['time_stamp'] = '2016-09-02 16:56:25';
$datetime1 = strtotime(date($key['time_stamp']));
$datetime2 = strtotime(date('Y-m-d H:m:s'));
$interval = $datetime2 - $datetime1;
$val = 45 * 60 * 1000;

if ($interval > $val) { }

或者你也可以使用表变量或CTE或IN和子查询，如果你有一个像ID这样的列

Answer 3

使用EXISTS

的多种合适方法

DELETE a 
FROM   lines a 
WHERE  EXISTS (SELECT 1 
               FROM   lines b 
               WHERE  a.documentnumber = b.documentnumber 
                      AND a.linenumber = b.linenumber 
                      AND a.sheetnumber = b.sheetnumber 
                      AND a.unit = b.unit 
               HAVING Count(*) > 1)

使用COUNT() OVER()

的另一种方法

;WITH cte 
     AS (SELECT id, 
                documentnumber, 
                linenumber, 
                sheetnumber, 
                unit, 
                CNT = Count(1) OVER(partition BY documentnumber, linenumber, sheetnumber, unit)
         FROM   dbo.lines) 
DELETE FROM cte 
WHERE  cnt > 1

注意：我的两种方法都会删除此组合documentnumber, linenumber, sheetnumber, unit的所有记录（如果它是重复的）

删除重复的行

3 个答案: