mysql行列转换

myskya

原始插入数据如下：
3 r# C+ u  `# j" f  _# p要求查询结果如下 ：
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7 ?9 O8 Z: D! S; I创建数据库、表

1. create database tests;
   
2. use tests;
   
3. create table t_score(
   
4. id int primary key auto_increment,
   
5. name varchar(20) not null,  #名字
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6. Subject varchar(10) not null, #科目
   
7. Fraction double default 0  #分数
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8. );

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添加数据

1. INSERT INTO `t_score`(name,Subject,Fraction) VALUES
   
2.          ('王海', '语文', 86),
   
3.         ('王海', '数学', 83),
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4.         ('王海', '英语', 93),
   
5.         ('陶俊', '语文', 88),
   
6.         ('陶俊', '数学', 84),
   
7.         ('陶俊', '英语', 94),
   
8.         ('刘可', '语文', 80),
   
9.         ('刘可', '数学', 86),
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10.         ('刘可', '英语', 88),
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11.         ('李春', '语文', 89),
    
12.         ('李春', '数学', 80),
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13.         ('李春', '英语', 87);

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方式一:使用if

1. select name as 名字 ,
   
2. sum(if(Subject='语文',Fraction,0)) as 语文,
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3. sum(if(Subject='数学',Fraction,0))as 数学,
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4. sum(if(Subject='英语',Fraction,0))as 英语,
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5. round(AVG(Fraction),2) as 平均分,
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6. SUM(Fraction) as 总分
   
7. from t_score group by name     
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8. union
   
9. select name as 名字 , sum(语文) Chinese,sum(数学) Math,sum(英语) English,round(AVG(总分),2)as 平均分,sum(总分) score  from(
   
10. select 'TOTAL' as name,
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11. sum(if(Subject='语文',Fraction,0)) as 语文,
    
12. sum(if(Subject='数学',Fraction,0))as 数学,
    
13. sum(if(Subject='英语',Fraction,0))as 英语,
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14. SUM(Fraction) as 总分
    
15. from t_score group by Subject )t

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方式二:使用case

1. select  name as Name,
   
2. sum(case when Subject = '语文' then Fraction end) as Chinese,
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3. sum(case when Subject = '数学' then Fraction end) as Math,
   
4. sum(case when Subject = '英语' then Fraction end) as English,
   
5. sum(fraction)as score
   
6. from t_score group by name
   
7. UNION ALL
   
8. select  name as Name,sum(Chinese) as Chinese,sum(Math) as Math,sum(English) as English,sum(score) as score from(
   
9. select 'TOTAL' as name,
   
10. sum(case when Subject = '语文' then Fraction end) as Chinese,
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11. sum(case when Subject = '数学' then Fraction end) as Math,
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12. sum(case when Subject = '英语' then Fraction end) as English,
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13. sum(fraction)as score
    
14. from t_score group by Subject)t

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方法三: with rollup

1. select
   
2.         ifnull(name,'TOll') name,
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3.         sum(if(Subject='语文',Fraction,0)) as 语文,
   
4.        sum(if(Subject='英语',Fraction,0)) as 英语,
   
5.        sum(if(Subject='数学',Fraction,0))as 数学,
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6.        sum(Fraction) 总分
   
7.         from t_score group by name with rollup

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查询结果如下：