【Teradata SQL】行转列、列转行的简单实现 多行转一列函数TDStats.udfConcat

1.多行转多列

行列转换就是如下图所示两种展示形式的互相转换

（1）使用PIVOT函数

SELECT *
FROM student
PIVOT (
 SUM(score) FOR subject IN (语文, 数学, 英语)
)

（2）使用Case When

SELECT name,
 MAX(
 CASE
 WHEN subject='语文'
 THEN score
 ELSE 0
 END) AS "语文",
 MAX(
 CASE
 WHEN subject='数学'
 THEN score
 ELSE 0
 END) AS "数学",
 MAX(
 CASE
 WHEN subject='英语'
 THEN score
 ELSE 0
 END) AS "英语"
FROM student
GROUP BY name

2.多列转多行

 

（1）使用UNPIVOT函数

SELECT *
FROM student1
UNPIVOT (
  score FOR subject IN ("语文","数学","英语")
)

（2）使用Case When

SELECT
  NAME,
  '语文' AS subject ,
  MAX("语文") AS score
FROM student1 GROUP BY NAME
UNION
SELECT
  NAME,
  '数学' AS subject ,
  MAX("数学") AS score
FROM student1 GROUP BY NAME
UNION
SELECT
  NAME,
  '英语' AS subject ,
  MAX("英语") AS score
FROM student1 GROUP BY NAME

3.多行转一列

 多行转一列函数TDStats.udfConcat

参考文档：

SQL行转列、列转行的简单实现