SQL查询仅获取两列中的结果集 [英] SQL query to get the resultset in two columns only

问题描述

我有这张桌子:

id  fName  lName   Address    PostCode  ContactNumber
-----------------------------------------------------
1  Tom     Daley   London     EC1 4EQ   075825485665
2  Jessica Ennis   Sheffield  SF2 3ER   075668956665
3  Joe     Bloggs  Glasgow    G3 2AZ    075659565666

我想要一个查询来给我这样的结果:

I want a query to give me the results like this:

id | label
1  | Tom
1  | Daley
1  | London
1  | EC1 4EQ
1  | 075825485665
2  | Jessica
2  | Ennis
2  | Sheffied   

依此类推.

请提供有关如何执行此操作的任何建议.

Any suggestions please on how to do this.

推荐答案

您可以使用 UNPIVOT函数把列变成行:

You can use the UNPIVOT function to turn the columns into rows:

select id, value
from yourtable
unpivot
(
  value
  for col in ([fName], [lName], [Address], [PostCode], [ContactNumber])
) unpiv

请参阅SQL Fiddle with Demo.

unpivot 将要求所有列的数据类型相同.因此，您可能必须对具有与此类似的不同数据类型的任何列执行 cast/convert:

The unpivot will require the datatype on all of the columns to be the same. So you might have to perform a cast/convert on any columns with different datatypes similar to this:

select id, value
from
(
  select id, [fName], [lName], [Address], [PostCode],
    cast([ContactNumber] as varchar(15)) [ContactNumber]
  from yourtable
) src
unpivot
(
  value
  for col in ([fName], [lName], [Address], [PostCode], [ContactNumber])
) unpiv;

参见SQL Fiddle with Demo.

从 SQL Server 2008 开始，这也可以使用带有 VALUES 的 CROSS APPLY 来编写:

Starting in SQL Server 2008, this can also be written using a CROSS APPLY with a VALUES:

select t.id,
  c.value
from yourtable t
cross apply
(
  values(fName), 
    (lName), 
    (Address), 
    (PostCode), 
    (cast(ContactNumber as varchar(15)))
) c (value)

参见SQL Fiddle with Demo

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