Oracle 行转列，列转行

一、行转列
1.1、初始测试数据

表结构：TEST_TB_GRADE

Sql代码:

1   create table TEST_TB_GRADE
2   (
3      ID        NUMBER(10) not null,
4      USER_NAME VARCHAR2(20 CHAR),
5      COURSE    VARCHAR2(20 CHAR),
6      SCORE     FLOAT
7   )

初始数据如下图：

1.2、如果需要实现如下的查询效果图：

这就是最常见的行转列，主要原理是利用decode函数、聚集函数(sum)，结合group by分组实现的，具体的sql如下：

Sql代码:
1   select t.user_name,
2      sum(decode(t.course, '语文', score,null)) as CHINESE,
3      sum(decode(t.course, '数学', score,null)) as MATH,
4      sum(decode(t.course, '英语', score,null)) as ENGLISH
5   from test_tb_grade t
6   group by t.user_name
7   order by t.user_name
1.3、延伸

如果要实现对各门功课的不同分数段进行统计，效果图如下：

具体的实现sql如下：
Sql代码:

01   select t2.SCORE_GP,
02      sum(decode(t2.course, '语文', COUNTNUM,null)) as CHINESE,
03      sum(decode(t2.course, '数学', COUNTNUM,null)) as MATH,
04      sum(decode(t2.course, '英语', COUNTNUM,null)) as ENGLISH
05   from (
06      select t.course,
07             case when t.score <60 then '00-60'
08                  when t.score >=60 and t.score <80 then '60-80'
09                  when t.score >=80 then '80-100' end as SCORE_GP,
10             count(t.score) as COUNTNUM
11      FROM test_tb_grade t
12      group by t.course,
13            case when t.score <60 then '00-60'
14                  when t.score >=60 and t.score <80 then '60-80'
15                  when t.score >=80 then '80-100' end
16      order by t.course ) t2
17   group by t2.SCORE_GP
18   order by t2.SCORE_GP
二、列转行

1.1、初始测试数据
表结构： TEST_TB_GRADE2
Sql代码:
1   create table TEST_TB_GRADE2
2   (
3      ID         NUMBER(10) not null,
4      USER_NAME VARCHAR2(20 CHAR),
5      CN_SCORE   FLOAT,
6      MATH_SCORE FLOAT,
7      EN_SCORE   FLOAT
8   )

初始数据如下图：

1.2、如果需要实现如下的查询效果图：

这就是最常见的列转行，主要原理是利用SQL里面的union，具体的sql语句如下：
Sql代码:

1   select user_name, 'CN_SCORE' COURSE , CN_SCORE as SCORE from test_tb_grade2
2   union
3   select user_name, 'MATH_SCORE' COURSE, MATH_SCORE as SCORE from test_tb_grade2
4   union
5   select user_name, 'EN_SCORE' COURSE, EN_SCORE as SCORE from test_tb_grade2
6   order by user_name,COURSE

也可以利用【insert all into ... select】来实现，首先需要先建一个表TEST_TB_GRADE3：
Sql代码:
1   create table TEST_TB_GRADE3
2   (
3          USER_NAME VARCHAR2(20 CHAR),
4          COURSE    VARCHAR2(20 CHAR),
5          SCORE     FLOAT
6   )

再执行下面的sql：
Sql代码:
1   insert all
2   into test_tb_grade3(USER_NAME,COURSE,SCORE) values(user_name, '语文', CN_SCORE)
3   into test_tb_grade3(USER_NAME,COURSE,SCORE) values(user_name, '数学', MATH_SCORE)
4   into test_tb_grade3(USER_NAME,COURSE,SCORE) values(user_name, '英语', EN_SCORE)
5   select user_name, CN_SCORE, MATH_SCORE, EN_SCORE from test_tb_grade2;
6   commit;

别忘记commit操作，然后再查询TEST_TB_GRADE3，发现表中的数据就是列转成行了。
原文地址：http://www.2cto.com/database/201108/100792.html

巴特西

Oracle 行转列，列转行

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