zoukankan      html  css  js  c++  java
  • mysql行列转换

    创建数据库、表

    create database tests;
    use tests;
    create table t_score(
    id int primary key auto_increment,
    name varchar(20) not null,  #名字
    Subject varchar(10) not null, #科目
    Fraction double default 0  #分数
    );

    添加数据

    INSERT INTO `t_score`(name,Subject,Fraction) VALUES
             ('王海', '语文', 86),
            ('王海', '数学', 83),
            ('王海', '英语', 93),
            ('陶俊', '语文', 88),
            ('陶俊', '数学', 84),
            ('陶俊', '英语', 94),
            ('刘可', '语文', 80),
            ('刘可', '数学', 86),
            ('刘可', '英语', 88),
            ('李春', '语文', 89),
            ('李春', '数学', 80),
            ('李春', '英语', 87);

     方式一:使用if

    select name as 名字 ,
    sum(if(Subject='语文',Fraction,0)) as 语文,
    sum(if(Subject='数学',Fraction,0))as 数学, 
    sum(if(Subject='英语',Fraction,0))as 英语,
    round(AVG(Fraction),2) as 平均分,
    SUM(Fraction) as 总分
    from t_score group by name     
    union
    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(
    select 'TOTAL' as name,
    sum(if(Subject='语文',Fraction,0)) as 语文,
    sum(if(Subject='数学',Fraction,0))as 数学, 
    sum(if(Subject='英语',Fraction,0))as 英语,
    SUM(Fraction) as 总分
    from t_score group by Subject )t

    方式二:使用case

    select  name as Name,
    sum(case when Subject = '语文' then Fraction end) as Chinese,
    sum(case when Subject = '数学' then Fraction end) as Math,
    sum(case when Subject = '英语' then Fraction end) as English,
    sum(fraction)as score
    from t_score group by name
    UNION ALL
    select  name as Name,sum(Chinese) as Chinese,sum(Math) as Math,sum(English) as English,sum(score) as score from(
    select 'TOTAL' as name,
    sum(case when Subject = '语文' then Fraction end) as Chinese,
    sum(case when Subject = '数学' then Fraction end) as Math,
    sum(case when Subject = '英语' then Fraction end) as English,
    sum(fraction)as score
    from t_score group by Subject)t

    方法三: with rollup

     select 
            ifnull(name,'TOll') name,
            sum(if(Subject='语文',Fraction,0)) as 语文,
           sum(if(Subject='英语',Fraction,0)) as 英语,
           sum(if(Subject='数学',Fraction,0))as 数学,
           sum(Fraction) 总分
            from t_score group by name with rollup

  • 相关阅读:
    C数据结构2.1-线性表抽象数据类型
    转载的内容
    转载springboot的内容
    jQuery中的load()Failed to load resource: the server responded with a status of 404 Maven框架遇到的问题
    java代码发送邮箱源代码
    Error:(1, 10) java: 需要class, interface或enum的错误
    性能测试系列五 压测常见的关注指标以及监控分析工具
    面试官常考的Selenium Web自动化面试题总结(上篇)
    性能测试系列四 压测指标的来源
    性能测试系列三 压测方式简单总结
  • 原文地址:https://www.cnblogs.com/weibanggang/p/9679301.html
Copyright © 2011-2022 走看看