3

所以，我知道足够多的 SQL 是危险的，并且正在按照一个示例从表中提取一页的记录：

SELECT TOP #arguments.perPage# * FROM (

SELECT DISTINCT ROW_NUMBER() OVER(ORDER BY (SELECT 1)) AS rownum, productdiagramparts.productdiagramid AS productdiagramid, products.id AS productid, products.title AS producttitle, totalRows = COUNT(*) OVER()
FROM manufacturers
INNER JOIN products ON manufacturers.id = products.manufacturerid
INNER JOIN productdiagramparts ON products.id = productdiagramparts.productid
INNER JOIN productdiagrams ON productdiagramparts.productdiagramid = productdiagrams.id
WHERE #whereClause#
) _tmpInlineView

WHERE rownum > #offset#
ORDER BY producttitle

围绕它的 SELECT TOP 当然只提取当前页面的记录。麻烦的是，我想删除的最里面的 SELECT 语句中有重复项，但是使用 DISTINCT 不能如上所示，因为行已经为外部查询编号。如何在对行编号之前使我最里面的 SELECT 结果不同？

这是基于以下公认答案的解决方案：

选择顶部#arguments.perPage# * FROM (

SELECT ROW_NUMBER() OVER(ORDER BY (SELECT 1)) AS rownum, productdiagramid, productid, producttitle, totalRows = COUNT(*) OVER() FROM (

SELECT DISTINCT productdiagramparts.productdiagramid AS productdiagramid, products.id AS productid, products.title AS producttitle FROM Manufacturers INNER JOIN products ON Manufacturers.id = products.manufacturerid INNER JOIN productdiagramparts ON products.id = productdiagramparts.productid INNER JOIN productdiagrams ON productdiagramparts.productdiagramid = productdiagrams.id WHERE #whereClause#

) _tmpDupRemove

) _tmpInlineView

WHERE rownum > #offset# ORDER BY producttitle

4

3 回答 3

1

这是第二次使用该ROW_NUMBER函数的方法。最内层SELECT根据重复组分配行号。然后，仅返回行号为 1 的行以删除重复项。最后，完成分配行号的过程。

SELECT TOP #arguments.perPage# *
FROM (

    SELECT ROW_NUMBER() OVER(ORDER BY (SELECT 1)) AS rownum,
        productdiagramparts.productdiagramid AS productdiagramid, 
        products.id AS productid, products.title AS producttitle, totalRows = COUNT(*) OVER()
    FROM (

        SELECT ROW_NUMBER() OVER PARTITION BY productdiagramparts.productdiagramid, products.id ORDER BY (SELECT 1)) AS dup_sequence, *
        FROM manufacturers
        INNER JOIN products ON manufacturers.id = products.manufacturerid
        INNER JOIN productdiagramparts ON products.id = productdiagramparts.productid
        INNER JOIN productdiagrams ON productdiagramparts.productdiagramid = productdiagrams.id
        WHERE #whereClause#

        ) _tmpDupRemove
    WHERE dup_sequence = 1

    ) _tmpInlineView

WHERE rownum > #offset#
ORDER BY producttitle
于 2013-02-18T16:35:24.907 回答
0 
DECLARE @startrow Int = 0
DECLARE @recsperpage Int = 10


SELECT  [Inner2].[productdiagramid], 
        [Inner2].[productid], 
        [Inner2].[producttitle]
FROM        
    (
    SELECT ROW_NUMBER() OVER 
        (ORDER BY  
              [Inner1].[producttitle]) AS [ROW_NUMBER], 
        [Inner1].[productdiagramid], 
        [Inner1].[productid], 
        [Inner1].[producttitle]
    FROM
        (
        SELECT DISTINCT pdp.productdiagramid, p.id as productid, p.title as producttitle
        FROM manufacturers m
        INNER JOIN products p ON m.id = p.manufacturerid
        INNER JOIN productdiagramparts pdp ON p.id = pdp.productid
        INNER JOIN productdiagrams pd ON pdp.productdiagramid = pd.id
        WHERE #whereclause#
        ) AS Inner1
    ) as Inner2
WHERE Inner2.[ROW_NUMBER] BETWEEN @startrow + 1 AND  @startrow + @recsperpage
ORDER BY [Inner2].[ROW_NUMBER]
于 2013-02-18T17:59:41.417 回答
0

您可以使用GROUP BY子句。

SQLServer 中的顺序：GROUP BY-->SELECT ROW_NUMBER()-->DISTINCT。因此 GROUP BY 而不是 DISTINCT 对您来说是必要的

SELECT TOP #arguments.perPage# * FROM (
SELECT ROW_NUMBER() OVER(ORDER BY (SELECT 1)) AS rownum, 
       productdiagramparts.productdiagramid AS productdiagramid, 
       products.id AS productid, 
       products.title AS producttitle, 
       totalRows = COUNT(*) OVER()
FROM manufacturers
INNER JOIN products ON manufacturers.id = products.manufacturerid
INNER JOIN productdiagramparts ON products.id = productdiagramparts.productid
INNER JOIN productdiagrams ON productdiagramparts.productdiagramid = productdiagrams.id
GROUP BY productdiagramparts.productdiagramid, products.id, products.title
WHERE #whereClause#
) _tmpInlineView
WHERE rownum > #offset#
ORDER BY producttitle
于 2013-02-18T16:43:50.353 回答