SQL 来自 WHERE 的多个 AS 列

Question

我有一个table

name | age | city
-------------
joe | 42 | berlin
ben | 42 | munich
anna | 22 | hamburg
pia | 50 | berlin
georg | 42 | munich
lisa | 42 | berlin

现在我想按城市在不同的列中获取所有 42 岁的人

berlin | munich
-------------
joe | ben
lisa | georg

所以我需要

SELECT (
SELECT  name AS berlin WHERE city = "berlin"
UNION
SELECT name AS munich WHERE city = "munich")
FROM TABLE
WHERE
age = 42

柏林最佳约尔格

Answer 1

我想你想要聚合：

select max(case when city = 'berlin' then name end) as berlin,
       max(case when city = 'munich' then name end) as munich
from (select t.*, row_number() over (partition by city order by name) as seqnum
      from t
      where city in ('berlin', 'munich') and age = 42
     ) t
group by seqnum
order by seqnum;

Answer 2

例如，使用 PIVOT 我用 SQL 服务器做到了。希望这可以帮到你。

DECLARE @columns varchar(MAX);
DECLARE @sql nvarchar(max)
CREATE TABLE #Table
(
idPerson int,
firstName varchar(10),
age int,
city varchar(10)
);

INSERT INTO #Table
SELECT '1', 'joe', '42','berlin' UNION ALL
SELECT '2', 'ben', '42','munich' UNION ALL
SELECT '3', 'Ana', '22','hamburg' UNION ALL
SELECT '4', 'pia', '50','berlin' UNION ALL
SELECT '5', 'george', '42','munich' UNION ALL
SELECT '6', 'lisa', '42','munich'



--SELECT * from #Table

 SET @columns = STUFF(
 (
 SELECT
   ',' + QUOTENAME(LTRIM(city))
 FROM
   (SELECT DISTINCT city
    FROM #Table
   ) AS T
 ORDER BY
 city
 FOR XML PATH('')
 ), 1, 1, '');

 SET @sql = N'
 SELECT
   * 
  FROM
  (  
  SELECT  idPerson ,firstName ,age ,city 
  FROM #Table
    --WHERE age = 42
  ) AS T
  PIVOT   
  (
  MAX(firstName)
  FOR city IN (' + @columns + N')
  ) AS P order by age;'; 

EXEC sp_executesql @sql;
DROP TABLE #Table;

Answer 3

感谢您的帮助！根据 Gordon Linhoff 的回答，我得到了这个解决方案：

SELECT max（city = 'berlin' then name end 的情况）作为柏林，最大（city = 'munich' then name end 的情况）作为慕尼黑来自 TABLE 其中年龄 = 42 ;

SQL 来自 WHERE 的多个 AS 列

SQL multiple AS columns from WHERE

sql

select

google-bigquery

where