SQL 行转列，列转行, 带SQL脚本方便大家验证.

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。