Unpivot with column name

问题

I have a table StudentMarks with columns Name, Maths, Science, English. Data is like

Name,  Maths, Science, English  
Tilak, 90,    40,      60  
Raj,   30,    20,      10

I want to get it arranged like the following:

Name,  Subject,  Marks
Tilak, Maths,    90
Tilak, Science,  40
Tilak, English,  60

With unpivot I am able to get Name, Marks properly, but not able to get the column name in the source table to the Subject column in the desired result set.

How can I achieve this?

I have so far reached the following query (to get Name, Marks)

select Name, Marks from studentmarks
Unpivot
(
  Marks for details in (Maths, Science, English)

) as UnPvt

回答1:

Your query is very close. You should be able to use the following which includes the subject in the final select list:

select u.name, u.subject, u.marks
from student s
unpivot
(
  marks
  for subject in (Maths, Science, English)
) u;

See SQL Fiddle with demo

回答2:

You may also try standard sql un-pivoting method by using a sequence of logic with the following code.. The following code has 3 steps:

create multiple copies for each row using cross join (also creating subject column in this case)
create column "marks" and fill in relevant values using case expression ( ex: if subject is science then pick value from science column)

remove any null combinations ( if exists, table expression can be fully avoided if there are strictly no null values in base table)

 select *
 from 
 (
    select name, subject,
    case subject
    when 'Maths' then maths
    when 'Science' then science
    when 'English' then english
    end as Marks
from studentmarks
Cross Join (values('Maths'),('Science'),('English')) AS Subjct(Subject)
)as D
where marks is not null;

回答3:

SELECT * FROM student

UNPIVOT(Marks FOR subjects in(Maths , Science , English));

回答4:

Another way around using cross join would be to specify column names inside cross join

select name, Subject, Marks 
from studentmarks
Cross Join (
values (Maths,'Maths'),(Science,'Science'),(English,'English')
) un(Marks, Subject)
where marks is not null;

来源：https://stackoverflow.com/questions/19055902/unpivot-with-column-name

标签

sql

sql-server

sql-server-2008

tsql

unpivot