行转列

新建表并插入数据：

create table t_grade

(name varchar2(50),

chinese_score number,

english_score number,

math_score number

);

insert into t_grade values ('张三',90,81,80);

insert into t_grade values ('李四',85,90,87);

commit;

select * from t_grade;

 

1、请把表格转换成下面的格式：

 

select name,'语文' as subject,chinese_score as result from t_grade union

select name,'英语' as subject,english_score as result from t_grade union

select name,'数学' as subject,math_score as result from t_grade

order by name

以Oracle中scott的emp为例，统计各职位的人员在各部门的人数分布情况，就可以用“行转列”：

 

使用“行转列”统计各职位的人员在各部门的分布人数后，数据为：

select t.job, count(decode(t.deptno, '10', 1)) as "10(DEPTNO)",

       count(decode(t.deptno, '20', 1)) as "20(DEPTNO)",

       count(decode(t.deptno, '30', 1)) as "30(DEPTNO)",

       count(decode(t.deptno, '40', 1)) as "40(DEPTNO)"

  from scott.emp t

  group by t.job;