Question

我确实想创建一个能够在列中选择多行的选择。如果一年不存在，则显示该年的NULL值

e.g。下表

CREATE TABLE [dbo].[MPG_TABLE](
[Driver] [char](40) NULL,
[Plate] [char](20) NOT NULL,
[Type] [char](20) NOT NULL,
[Build] [char](6) NULL,
[Miles] [float] NULL,
[Gallon] [float] NULL,
[MPG] [numeric](8, 2) NULL
) ON [PRIMARY]

填写表格：

insert into MPG_TABLE (Driver, Plate, Type, Build, Miles, Gallon)  
values ('JOHN', 'AAAA', '4X4', '2010', 20000, 2100), 
('JOHN', 'AAAA', '4X4', '2011', 30000, 2900),
('JOHN', 'AAAA', '4X4', '2012', 25000, 2300),
('JOHN', 'AAAA', '4X4', '2013', 21420, 2130),
('PETER', 'BBBB', 'LUXE', '2011', 22040, 1650),
('PETER', 'BBBB', 'LUXE', '2012', 24000, 1800), 
('JACK', 'CCCC', 'LORRY', '2009', 180040, 96005),       
('JACK', 'CCCC', 'LORRY', '2010', 220040, 100005),
('JACK', 'CCCC', 'LORRY', '2011', 240000, 100235), 
('ADRIAN', 'EEEE', 'LUXE', '2010', 19040, 1450),
('ADRIAN', 'EEEE', 'LUXE', '2011', 30000, 2200),         
('ADRIAN', 'DDDD', 'LUXE', '2012', 22040, 1650),
('ADRIAN', 'DDDD', 'LUXE', '2013', 24000, 1800),  
('JERRY', 'FFFF', 'LUXE', '2013', 2000, 100)

现在更新最后一栏：

update MPG_TABLE
set MPG = (Miles / Gallon)

我有类似的东西，但它没有显示我想要的东西：

select distinct c.Driver, c.Plate, c.Type, a.build, a.Miles, a.gallon, 
a.mpg, b.build, b.miles,  b.gallon, b.mpg, c.build, c.miles, c.gallon, c.mpg  
from MPG_TABLE as a left outer join MPG_TABLE as b 
on ISNULL(a.Driver, null) = ISNULL(b.driver, null),
MPG_TABLE as c    
where a.Build = '2012'
and b.Build = '2013' 
and c.Build = '2011'

结果应如下所示：

                          2009                    2010                      2011
Driver    Plate   Type    Miles   Gallon  MPG     Miles    Gallon   MPG     Miles
JOHN      AAAA    4X4     NULL    NULL    NULL    20000    2100     9.52    30000
PETER     BBBB    LUXE    NULL    NULL    NULL    NULL     NULL     NULL    22040
JACK      CCCC    LORRY   180040  96005   1.88    220040   100005   2.2     240000
ADRIAN    EEEE    LUXE    NULL    NULL    NULL    19040    1450     13.13   30000
ADRIAN    DDDD    LUXE    NULL    NULL    NULL    NULL     NULL     NULL    NULL
JERRY     FFFF    LUXE    NULL    NULL    NULL    NULL     NULL     NULL    NULL

如何为此创建选择？

Answer 1

尝试此查询：

select Driver, Plate, Type
    , min(case Build when '2009' then Miles end) as Miles2009
    , min(case Build when '2009' then Gallon end) as Gallon2009
    , min(case Build when '2009' then MPG end) as MPG2009
    , min(case Build when '2010' then Miles end) as Miles2010
    , min(case Build when '2010' then Gallon end) as Gallon2010
    , min(case Build when '2010' then MPG end) as MPG2010
    , min(case Build when '2011' then Miles end) as Miles2011
    , min(case Build when '2011' then Gallon end) as Gallon2011
    , min(case Build when '2011' then MPG end) as MPG2011
    , min(case Build when '2012' then Miles end) as Miles2012
    , min(case Build when '2012' then Gallon end) as Gallon2012
    , min(case Build when '2012' then MPG end) as MPG2012
    , min(case Build when '2013' then Miles end) as Miles2013
    , min(case Build when '2013' then Gallon end) as Gallon2013
    , min(case Build when '2013' then MPG end) as MPG2013
from MPG_TABLE t
cross join (values(1),(2),(3),(4),(5))b(b) -- number of years you want to display
group by Driver, Plate, Type

但请记住一件重要的事情：像这样的转动应始终在客户端完成，不在服务器上 !!!

Answer 2

试试这个：

CREATE TABLE #MPG_TABLE(
[Driver] [char](40) NULL,
[Plate] [char](20) NOT NULL,
[Type] [char](20) NOT NULL,
[Build] [char](6) NULL,
[Miles] [float] NULL,
[Gallon] [float] NULL,
[MPG] [numeric](8, 2) NULL
) ON [PRIMARY]

insert into #MPG_TABLE (Driver, Plate, Type, Build, Miles, Gallon)  
values ('JOHN', 'AAAA', '4X4', '2010', 20000, 2100), 
('JOHN', 'AAAA', '4X4', '2011', 30000, 2900),
('JOHN', 'AAAA', '4X4', '2012', 25000, 2300),
('JOHN', 'AAAA', '4X4', '2013', 21420, 2130),
('PETER', 'BBBB', 'LUXE', '2011', 22040, 1650),
('PETER', 'BBBB', 'LUXE', '2012', 24000, 1800), 
('JACK', 'CCCC', 'LORRY', '2009', 180040, 96005),       
('JACK', 'CCCC', 'LORRY', '2010', 220040, 100005),
('JACK', 'CCCC', 'LORRY', '2011', 240000, 100235), 
('ADRIAN', 'EEEE', 'LUXE', '2010', 19040, 1450),
('ADRIAN', 'EEEE', 'LUXE', '2011', 30000, 2200),         
('ADRIAN', 'DDDD', 'LUXE', '2012', 22040, 1650),
('ADRIAN', 'DDDD', 'LUXE', '2013', 24000, 1800),  
('JERRY', 'FFFF', 'LUXE', '2013', 2000, 100) 


update #MPG_TABLE
set MPG = (Miles / Gallon)

Declare @cols varchar(MAX),
    @query VARCHAR(MAX)



select @cols=STUFF((SELECT ', [' + New_Col + ']'
   FROM ( 
        select distinct case 
            when COL='Miles' then CAST(Build as varchar) + 'Miles'
            when COL='Gallon' then CAST(Build as varchar) + 'Gallon'
            when COL='MPG' then CAST(Build as varchar) + 'MPG'
        end New_Col
        from (select Driver
                    ,Plate
                    ,[Type]
                    ,Build
                    ,CAST(Miles as varchar) Miles
                    ,CAST(Gallon as varchar) Gallon
                    ,CAST(MPG as varchar) MPG 
                    from #MPG_TABLE
             )a

        UNPIVOT
        (
            Value
            for COL in ([Miles],[Gallon],[MPG])
        )UPVT
     )a   
    for XML Path('')), 1, 2, '');

print @cols;

Set @query= 'select  * from 
    (select  Driver
        ,Plate
        ,[Type]
        ,case 
            when COL=''Miles'' then CAST(Build as varchar) + ''Miles''
            when COL=''Gallon'' then CAST(Build as varchar) + ''Gallon''
            when COL=''MPG'' then CAST(Build as varchar) + ''MPG''
        end New_Col,    
            Value
        from (select Driver
                    ,Plate
                    ,[Type]
                    ,Build
                    ,CAST(Miles as varchar) Miles
                    ,CAST(Gallon as varchar) Gallon
                    ,CAST(MPG as varchar) MPG 
                    from #MPG_TABLE
             )a

        UNPIVOT
        (
            Value
            for COL in ([Miles],[Gallon],[MPG])
        )UPVT
    )b
pivot
(
  MAX(Value)
  for New_Col in ('+@cols+')

) PVT   '




exec(@query)

在SQL Server中显示的列中选择多行也为NULL

2 个答案: