LeetCode 618. Students Report By Geography

drop table student
create Table student (name varchar(25),continent varchar(25));

insert into student values('Jack','America')
insert into student values('Pascal','Europe')
insert into student values('Xi','Asia')
insert into student values('Jane','America')

A U.S graduate school has students from Asia, Europe and America. The students' location information are stored in table student as below.

 

| name   | continent |
|--------|-----------|
| Jack   | America   |
| Pascal | Europe    |
| Xi     | Asia      |
| Jane   | America   |

 

Pivot the continent column in this table so that each name is sorted alphabetically and displayed underneath its corresponding continent. The output headers should be America, Asia and Europe respectively. It is guaranteed that the student number from America is no less than either Asia or Europe.

 

For the sample input, the output is:

 

| America | Asia | Europe |
|---------|------|--------|
| Jack    | Xi   | Pascal |
| Jane    |      |        |

SELECT
  America,
  Asia,
  Europe
FROM
  (SELECT
     row_number() OVER (PARTITION BY continent order by name) AS asid,
     name AS Asia
   FROM
     student
   WHERE
     continent = 'Asia'
   ) AS t1
  RIGHT JOIN
  (SELECT
     row_number()
     OVER (PARTITION BY continent order by name) AS amid,
     name                          AS America
   FROM
     student
   WHERE
     continent = 'America'
   ) AS t2 ON asid = amid
  LEFT JOIN
  (SELECT
     row_number()
     OVER (PARTITION BY continent order by name) AS euid,
     name                          AS Europe
   FROM
     student
   WHERE
     continent = 'Europe'
  ) AS t3 ON amid = euid;

 

declare @as int
declare @am int
declare @eu int
set @as=0;
set @am=0;
set @eu=0;
SELECT 
    [America], [Asia], [Europe]
FROM
    (SELECT
        @as + 1 AS asid, name AS Asia
    FROM
        student
    WHERE
        continent = 'Asia'
) AS t1
        RIGHT JOIN
    (SELECT 
        @am + 1 AS amid, name AS America
    FROM
        student
    WHERE
        continent = 'America'
) AS t2 ON asid = amid
        LEFT JOIN
    (SELECT 
        @eu + 1 AS euid, name AS Europe
    FROM
        student
    WHERE
        continent = 'Europe'
) AS t3 ON amid = euid

 

select
  (case when continent = 'America' then name else '' end) America,
  (case when continent = 'Europe' then name else '' end) Europe,
  (case when continent = 'Asia' then name else '' end) Asia
from student

select [America],[Europe],[Asia]
from (select name,continent from student) as D
pivot(min(name) for continent in ([America],[Europe],[Asia]) ) as P