Oracle中简单的关联查询

Question

请看清题目要求再做  O(∩_∩)O

Answer 1

-- 图片不清楚，眼晕select name ,
       SUM(decode(course,'语文',score,0)) 语文,
       SUM(decode(course,'数学',score,0)) 数学,
       SUM(decode(course,'英语',score,0)) 英语
  from t
 group by name        
       

Answer 2

基本的行列转换
select name ,
       SUM(decode(course,'语文',score,‘null')) 语文,
       SUM(decode(course,'数学',score,‘null')) 数学,
       SUM(decode(course,'英语',score,‘null')) 英语
  from t
 group by name

Answer 3

select name ,
       SUM(decode(course,'语文',score,'null')) 语文,
       SUM(decode(course,'数学',score,'null')) 数学,
       SUM(decode(course,'英语',score,'null')) 英语
  from orade
 group by name

Answer 4

学习了，DECODE函数

Answer 5

 null值上加引号.

Answer 6

null值上不能加引号

Answer 7

凡是说不会做，肯定是没有亲自写过sql去尝试的，那你这个学习很是被动啊

Answer 8

最基本的SQL查询，简单的关联查询！

Answer 9

select name ,
       SUM(decode(course,'yuwen',score,0)) 'yuwen,
       SUM(decode(course,'shuxue',score,0)) shuxue,
       SUM(decode(course,'yingyu',score,0)) yingyu
  from grate
 group by name