Oracle行列转换小结

目录结构如下：

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

create table TEST_TB_GRADE

(

ID NUMBER(10) not null,

USER_NAME VARCHAR2(20 CHAR),

COURSE VARCHAR2(20 CHAR),

SCORE FLOAT

)

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

select t.user_name,

sum(decode(t.course, '语文', score,null)) as CHINESE,

sum(decode(t.course, '数学', score,null)) as MATH,

sum(decode(t.course, '英语', score,null)) as ENGLISH

from test_tb_grade t

group by t.user_name

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

select t2.SCORE_GP,

sum(decode(t2.course, '语文', COUNTNUM,null)) as CHINESE,

sum(decode(t2.course, '数学', COUNTNUM,null)) as MATH,

sum(decode(t2.course, '英语', COUNTNUM,null)) as ENGLISH

from (

select t.course,

case when t.score <60 then '00-60'

when t.score >=60 and t.score <80 then '60-80'

when t.score >=80 then '80-100' end as SCORE_GP,

count(t.score) as COUNTNUM

FROM test_tb_grade t

group by t.course,

case when t.score <60 then '00-60'

when t.score >=60 and t.score <80 then '60-80'

when t.score >=80 then '80-100' end

order by t.course ) t2

group by t2.SCORE_GP

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

create table TEST_TB_GRADE2

(

ID NUMBER(10) not null,

USER_NAME VARCHAR2(20 CHAR),

CN_SCORE FLOAT,

MATH_SCORE FLOAT,

EN_SCORE FLOAT

)

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

select user_name, '语文' COURSE , CN_SCORE as SCORE from test_tb_grade2

union select user_name, '数学' COURSE, MATH_SCORE as SCORE from test_tb_grade2

union select user_name, '英语' COURSE, EN_SCORE as SCORE from test_tb_grade2

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

create table TEST_TB_GRADE3

(

USER_NAME VARCHAR2(20 CHAR),

COURSE VARCHAR2(20 CHAR),

SCORE FLOAT

)

再执行下面的sql：

Sql代码

insert all

into test_tb_grade3(USER_NAME,COURSE,SCORE) values(user_name, '语文', CN_SCORE)

into test_tb_grade3(USER_NAME,COURSE,SCORE) values(user_name, '数学', MATH_SCORE)

into test_tb_grade3(USER_NAME,COURSE,SCORE) values(user_name, '英语', EN_SCORE)

select user_name, CN_SCORE, MATH_SCORE, EN_SCORE from test_tb_grade2;

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。