sql 面试题

drop table if exists STU_SCORE;
create table STU_SCORE
(
name                 varchar(50) comment '姓名',
subject              varchar(50) comment '课程',
score                numeric(11,2) comment '分数',
stuid                int comment '学号'
)ENGINE = MYISAM DEFAULT CHARACTER SET = utf8 COLLATE = utf8_bin;
alter table STU_SCORE comment '学生成绩表';

INSERT into STU_SCORE VALUES('张三','数学',89,1);
INSERT into STU_SCORE VALUES('张三','语文',90,1);
INSERT into STU_SCORE VALUES('张三','英语',50,1);
INSERT into STU_SCORE VALUES('李四','数学',90,2);
INSERT into STU_SCORE VALUES('李四','语文',93,2);
INSERT into STU_SCORE VALUES('李四','英语',80,2);
INSERT into STU_SCORE VALUES('王五','数学',95,3);
INSERT into STU_SCORE VALUES('王五','语文',59,3);
INSERT into STU_SCORE VALUES('王五','英语',88,3);
INSERT into STU_SCORE VALUES('赵六','数学',98,4);
INSERT into STU_SCORE VALUES('赵六','语文',69,4);
INSERT into STU_SCORE VALUES('赵六','英语',78,4);

1.1. 计算每个人的总成绩并排名(要求显示字段: 学号，姓名，总成绩)

    

#1.1.计算每个人的总成绩并排名(要求显示字段: 学号，姓名，总成绩)
SELECT stuid AS '学号', name AS '姓名',SUM(score) AS '总成绩'
FROM STU_SCORE GROUP BY stuid ORDER BY '总成绩' DESC

1.2. 列出各门课程成绩最好的学生(要求显示字段: 学号，姓名,科目，最高分

     

#1.2.列出各门课程成绩最好的学生(要求显示字段: 学号，姓名,科目，最高分
SELECT stuid AS '学号', name AS '姓名' ,`subject` AS '科目',MAX(score) AS '最高分'
FROM STU_SCORE  GROUP BY SUBJECT  ORDER BY '最高分' DESC

1.3. 统计如下：学号     姓名     语文     数学     英语     总分     平均分

   

#1.3.统计：学号     姓名     语文     数学     英语     总分     平均分
SELECT stuid as '学号',name as '姓名',
sum(case when subject='语文' then score else 0 end) as '语文',
sum(case when subject='数学' then score else 0 end) as '数学',
sum(case when subject='英语' then score else 0 end) as '英语',
sum(score) as '总分',
(sum(score)/count(1)) as '平均分'
FROM STU_SCORE GROUP BY stuid ORDER BY 总分 DESC

1.4. 统计如下：课程     不及格（0-59）    良（60-80）    优（81-100）

    

#1.4.统计如下：课程     不及格（0-59）    良（60-80）    优（81-100）
SELECT subject AS '课程',
(SELECT count(1) FROM STU_SCORE WHERE score<60 AND subject=t1.subject) AS '不及格',
(SELECT count(1) FROM STU_SCORE WHERE score BETWEEN 60 AND 80 AND subject = t1.subject) AS '良',
(SELECT count(1) FROM STU_SCORE WHERE score >80 AND subject=t1.subject) AS '优'
FROM STU_SCORE t1 GROUP BY subject

1.5. 统计如下

     

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