Question

我希望从SQL Server表中区分出两列。我得到了这个结果 - 我可以优化这个查询吗？

create TABLE #Temporary_tbl
(                              
    ProductColour VARCHAR(50),
    ProductSize VARCHAR(20),
)

insert into #Temporary_tbl (ProductColour)
   select distinct productcolour
   from shoptransfer

insert into #Temporary_tbl (ProductSize)
   select distinct ProductSize
   from shoptransfer

select * from #Temporary_tbl

我试试这个：

select distinct ProductColour, null as ProductSize
from shoptransfer

union all

select distinct null as ProductColor, ProductSize
from shoptransfer

Answer 1

我认为问题是你的期望：我猜想要一个不同的颜色列表和一个不同的尺寸列表，但是你希望它们出现在同一个结果表中，如下所示：

Colour      Size
blue        10
green       12
orange      14

即使蓝色和蓝色之间没有任何关系10号等等。这不是一个很好的数据表示，因为当有5种颜色但100种尺寸时会发生什么。

您可以通过单独选择每个DISTINCT列表以及ROW_NUMBER（）然后加入行号来完成此操作。这不是SQL的用途，但我可以理解，有时你会因为报告原因而想做这类事情。

例如

select productSize, productColour
from ( 
    -- get the colours and a row number
    select productColour, row_number() over ( order by productColour ) as rownum
    from ( select distinct productColour from shoptransfer ) as c1
) as colours
-- full outer join so the row numbers match and you get all the rows from both
full outer join ( 
    -- get the sizes and a row number
    select productSize, row_number() over ( order by productSize ) as rownum
    from ( select distinct productSize from shoptransfer ) as s1
) as sizes
on colours.rownum = sizes.rownum

Answer 2

;WITH CTE AS
(
 select  ProductColour  , null as ProductSize
 from shoptransfer
 GROUP BY ProductColour

 union all

 select  null as ProductColor, ProductSize
 from shoptransfer
 GROUP BY ProductSize
)
SELECT * FROM CTE

Answer 3

取决于你想如何在这里提供数据其他建议可能+ PIVOT

   select * from (
    SELECT  distinct       
     [ProductColor] as 'tata_column', 'ProductColor' as 'P_TAG'    
    FROM shoptransfer
 union all
     SELECT  distinct
     [ProductSize] as 'data_colunm'  , 'ProductSize' as 'P_TAG'
   FROM shoptransfer
   ) A

我将消除TEMP表以更快地运行它

请注意使用＆＃34; WITH CLAUSE＆＃34;随着巨大的记录设置将缓慢下降，可能会崩溃服务器!!!

优化SQL Server中的SELECT查询

3 个答案: