精华内容
下载资源
问答
  • sql语句练习50题(Mysql版)

    万次阅读 多人点赞 2017-12-19 00:11:31
    习题来源于网络,sql语句是自己写的。欢迎指正。 表名和字段 –1.学生表 Student(s_id,s_name,s_birth,s_sex) –学生编号,学生姓名, 出生年月,学生性别 –2.课程表 Course(c_id,c_name,t_id) – –课程编号, ...

    习题来源于网络,sql语句是自己写的,部分有参考。欢迎指正。


    2019.3.29更新
    写完后一年没有看过,没想到这篇文章有这么多人点击。博主工作到一半去考研了,目前已上岸某中部985,也算是比较幸运。非常感谢大家在评论里的留言,留言太多不能一一回复,希望大家见谅。这两天根据评论把文章中的某些错误或者不足的地方更新了下,,希望大家能够继续指出不足之处。


    表名和字段

    –1.学生表
    Student(s_id,s_name,s_birth,s_sex) --学生编号,学生姓名, 出生年月,学生性别
    –2.课程表
    Course(c_id,c_name,t_id) – --课程编号, 课程名称, 教师编号
    –3.教师表
    Teacher(t_id,t_name) --教师编号,教师姓名
    –4.成绩表
    Score(s_id,c_id,s_score) --学生编号,课程编号,分数

    测试数据

    --建表
    --学生表
    CREATE TABLE `Student`(
    	`s_id` VARCHAR(20),
    	`s_name` VARCHAR(20) NOT NULL DEFAULT '',
    	`s_birth` VARCHAR(20) NOT NULL DEFAULT '',
    	`s_sex` VARCHAR(10) NOT NULL DEFAULT '',
    	PRIMARY KEY(`s_id`)
    );
    --课程表
    CREATE TABLE `Course`(
    	`c_id`  VARCHAR(20),
    	`c_name` VARCHAR(20) NOT NULL DEFAULT '',
    	`t_id` VARCHAR(20) NOT NULL,
    	PRIMARY KEY(`c_id`)
    );
    --教师表
    CREATE TABLE `Teacher`(
    	`t_id` VARCHAR(20),
    	`t_name` VARCHAR(20) NOT NULL DEFAULT '',
    	PRIMARY KEY(`t_id`)
    );
    --成绩表
    CREATE TABLE `Score`(
    	`s_id` VARCHAR(20),
    	`c_id`  VARCHAR(20),
    	`s_score` INT(3),
    	PRIMARY KEY(`s_id`,`c_id`)
    );
    --插入学生表测试数据
    insert into Student values('01' , '赵雷' , '1990-01-01' , '男');
    insert into Student values('02' , '钱电' , '1990-12-21' , '男');
    insert into Student values('03' , '孙风' , '1990-05-20' , '男');
    insert into Student values('04' , '李云' , '1990-08-06' , '男');
    insert into Student values('05' , '周梅' , '1991-12-01' , '女');
    insert into Student values('06' , '吴兰' , '1992-03-01' , '女');
    insert into Student values('07' , '郑竹' , '1989-07-01' , '女');
    insert into Student values('08' , '王菊' , '1990-01-20' , '女');
    --课程表测试数据
    insert into Course values('01' , '语文' , '02');
    insert into Course values('02' , '数学' , '01');
    insert into Course values('03' , '英语' , '03');
    
    --教师表测试数据
    insert into Teacher values('01' , '张三');
    insert into Teacher values('02' , '李四');
    insert into Teacher values('03' , '王五');
    
    --成绩表测试数据
    insert into Score values('01' , '01' , 80);
    insert into Score values('01' , '02' , 90);
    insert into Score values('01' , '03' , 99);
    insert into Score values('02' , '01' , 70);
    insert into Score values('02' , '02' , 60);
    insert into Score values('02' , '03' , 80);
    insert into Score values('03' , '01' , 80);
    insert into Score values('03' , '02' , 80);
    insert into Score values('03' , '03' , 80);
    insert into Score values('04' , '01' , 50);
    insert into Score values('04' , '02' , 30);
    insert into Score values('04' , '03' , 20);
    insert into Score values('05' , '01' , 76);
    insert into Score values('05' , '02' , 87);
    insert into Score values('06' , '01' , 31);
    insert into Score values('06' , '03' , 34);
    insert into Score values('07' , '02' , 89);
    insert into Score values('07' , '03' , 98);
    

    练习题和sql语句

    -- 1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数	
    	
    select a.* ,b.s_score as 01_score,c.s_score as 02_score from 
    student a 
    	join score b on a.s_id=b.s_id and b.c_id='01'
    	left join score c on a.s_id=c.s_id and c.c_id='02' or c.c_id = NULL where b.s_score>c.s_score
    	
    --也可以这样写
    	select a.*,b.s_score as 01_score,c.s_score as 02_score from student 		  a,score b,score c 
    			where a.s_id=b.s_id 
    			and a.s_id=c.s_id 
    			and b.c_id='01' 
    			and c.c_id='02' 
    			and b.s_score>c.s_score
    -- 2、查询"01"课程比"02"课程成绩低的学生的信息及课程分数
    	
    select a.* ,b.s_score as 01_score,c.s_score as 02_score from 
    	student a left join score b on a.s_id=b.s_id and b.c_id='01' or b.c_id=NULL 
    	 join score c on a.s_id=c.s_id and c.c_id='02' where b.s_score<c.s_score
    			
    
    -- 3、查询平均成绩大于等于60分的同学的学生编号和学生姓名和平均成绩
    select b.s_id,b.s_name,ROUND(AVG(a.s_score),2) as avg_score from 
    	student b 
    	join score a on b.s_id = a.s_id
    	GROUP BY b.s_id,b.s_name HAVING avg_score >=60;
    	
    
    -- 4、查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩
    		-- (包括有成绩的和无成绩的)
    		
    select b.s_id,b.s_name,ROUND(AVG(a.s_score),2) as avg_score from 
    	student b 
    	left join score a on b.s_id = a.s_id
    	GROUP BY b.s_id,b.s_name HAVING avg_score <60
    	union
    select a.s_id,a.s_name,0 as avg_score from 
    	student a 
    	where a.s_id not in (
    				select distinct s_id from score);
    
    
    -- 5、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩
    select a.s_id,a.s_name,count(b.c_id) as sum_course,sum(b.s_score) as sum_score from 
    	student a 
    	left join score b on a.s_id=b.s_id
    	GROUP BY a.s_id,a.s_name;
    			
    			
    -- 6、查询"李"姓老师的数量 
    select count(t_id) from teacher where t_name like '李%';
    	
    -- 7、查询学过"张三"老师授课的同学的信息 
    select a.* from 
    	student a 
    	join score b on a.s_id=b.s_id where b.c_id in(
    		select c_id from course where t_id =(
    			select t_id from teacher where t_name = '张三'));
    
    -- 8、查询没学过"张三"老师授课的同学的信息 
    select * from 
        student c 
        where c.s_id not in(
            select a.s_id from student a join score b on a.s_id=b.s_id where b.c_id in(
            select a.c_id from course a join teacher b on a.t_id = b.t_id where t_name ='张三'));
    -- 9、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息
    
    select a.* from 
    	student a,score b,score c 
    	where a.s_id = b.s_id  and a.s_id = c.s_id and b.c_id='01' and c.c_id='02';
    	
    -- 10、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
    			
    select a.* from 
    	student a 
    	where a.s_id in (select s_id from score where c_id='01' ) and a.s_id not in(select s_id from score where c_id='02')
    			
    
    -- 11、查询没有学全所有课程的同学的信息 
    --@wendiepei的写法
    select s.* from student s 
    left join Score s1 on s1.s_id=s.s_id
    group by s.s_id having count(s1.c_id)<(select count(*) from course)	
    --@k1051785839的写法
    select *
    from student
    where s_id not in(
    select s_id from score t1  
    group by s_id having count(*) =(select count(distinct c_id)  from course)) 
    -- 12、查询至少有一门课与学号为"01"的同学所学相同的同学的信息 
    
    select * from student where s_id in(
    	select distinct a.s_id from score a where a.c_id in(select a.c_id from score a where a.s_id='01')
    	);
    			
    -- 13、查询和"01"号的同学学习的课程完全相同的其他同学的信息 
    --@ouyang_1993的写法
    SELECT
     Student.*
    FROM
     Student
    WHERE
     s_id IN (SELECT s_id FROM Score GROUP BY s_id HAVING COUNT(s_id) = (
        #下面的语句是找到'01'同学学习的课程数
        SELECT COUNT(c_id) FROM Score WHERE s_id = '01'
       )
     )
    AND s_id NOT IN (
     #下面的语句是找到学过‘01’同学没学过的课程,有哪些同学。并排除他们
     SELECT s_id FROM Score
     WHERE c_id IN(
       #下面的语句是找到‘01’同学没学过的课程
       SELECT DISTINCT c_id FROM Score
       WHERE c_id NOT IN (
         #下面的语句是找出‘01’同学学习的课程
         SELECT c_id FROM Score WHERE s_id = '01'
        )
      ) GROUP BY s_id
    ) #下面的条件是排除01同学
    AND s_id NOT IN ('01')
    --@k1051785839的写法
    SELECT
     t3.*
    FROM
     (
      SELECT
       s_id,
       group_concat(c_id ORDER BY c_id) group1
      FROM
       score
      WHERE
       s_id &lt;> '01'
      GROUP BY
       s_id
     ) t1
    INNER JOIN (
     SELECT
      group_concat(c_id ORDER BY c_id) group2
     FROM
      score
     WHERE
      s_id = '01'
     GROUP BY
      s_id
    ) t2 ON t1.group1 = t2.group2
    INNER JOIN student t3 ON t1.s_id = t3.s_id
    
    -- 14、查询没学过"张三"老师讲授的任一门课程的学生姓名 
    select a.s_name from student a where a.s_id not in (
    	select s_id from score where c_id = 
    				(select c_id from course where t_id =(
    					select t_id from teacher where t_name = '张三')));
    
    -- 15、查询两门及其以上不及格课程的同学的学号,姓名及其平均成绩 
    select a.s_id,a.s_name,ROUND(AVG(b.s_score)) from 
    	student a 
    	left join score b on a.s_id = b.s_id
    	where a.s_id in(
    			select s_id from score where s_score<60 GROUP BY  s_id having count(1)>=2)
    	GROUP BY a.s_id,a.s_name
    
    -- 16、检索"01"课程分数小于60,按分数降序排列的学生信息
    select a.*,b.c_id,b.s_score from 
    	student a,score b 
    	where a.s_id = b.s_id and b.c_id='01' and b.s_score<60 ORDER BY b.s_score DESC;
    		
    -- 17、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
    select a.s_id,(select s_score from score where s_id=a.s_id and c_id='01') as 语文,
    				(select s_score from score where s_id=a.s_id and c_id='02') as 数学,
    				(select s_score from score where s_id=a.s_id and c_id='03') as 英语,
    			round(avg(s_score),2) as 平均分 from score a  GROUP BY a.s_id ORDER BY 平均分 DESC;
    --@喝完这杯还有一箱的写法
    SELECT a.s_id,MAX(CASE a.c_id WHEN '01' THEN a.s_score END ) 语文, 
    MAX(CASE a.c_id WHEN '02' THEN a.s_score END ) 数学, 
    MAX(CASE a.c_id WHEN '03' THEN a.s_score END ) 英语, 
    avg(a.s_score),b.s_name FROM Score a JOIN Student b ON a.s_id=b.s_id GROUP BY a.s_id ORDER BY 5 DESC		
    -- 18.查询各科成绩最高分、最低分和平均分:以如下形式显示:课程ID,课程name,最高分,最低分,平均分,及格率,中等率,优良率,优秀率
    --及格为>=60,中等为:70-80,优良为:80-90,优秀为:>=90
    select a.c_id,b.c_name,MAX(s_score),MIN(s_score),ROUND(AVG(s_score),2),
    	ROUND(100*(SUM(case when a.s_score>=60 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 及格率,
    	ROUND(100*(SUM(case when a.s_score>=70 and a.s_score<=80 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 中等率,
    	ROUND(100*(SUM(case when a.s_score>=80 and a.s_score<=90 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 优良率,
    	ROUND(100*(SUM(case when a.s_score>=90 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 优秀率
    	from score a left join course b on a.c_id = b.c_id GROUP BY a.c_id,b.c_name
    	
    -- 19、按各科成绩进行排序,并显示排名
    -- mysql没有rank函数
    	select a.s_id,a.c_id,
            @i:=@i +1 as i保留排名,
            @k:=(case when @score=a.s_score then @k else @i end) as rank不保留排名,
            @score:=a.s_score as score
        from (
            select s_id,c_id,s_score from score GROUP BY s_id,c_id,s_score ORDER BY s_score DESC
    )a,(select @k:=0,@i:=0,@score:=0)s
    --@k1051785839的写法
    (select * from (select 
    t1.c_id,
    t1.s_score,
    (select count(distinct t2.s_score) from score t2 where t2.s_score>=t1.s_score and t2.c_id='01') rank
    FROM score t1 where t1.c_id='01'
    order by t1.s_score desc) t1)
    union
    (select * from (select 
    t1.c_id,
    t1.s_score,
    (select count(distinct t2.s_score) from score t2 where t2.s_score>=t1.s_score and t2.c_id='02') rank
    FROM score t1 where t1.c_id='02'
    order by t1.s_score desc) t2)
    union
    (select * from (select 
    t1.c_id,
    t1.s_score,
    (select count(distinct t2.s_score) from score t2 where t2.s_score>=t1.s_score and t2.c_id='03') rank
    FROM score t1 where t1.c_id='03'
    order by t1.s_score desc) t3)
    -- 20、查询学生的总成绩并进行排名
    select a.s_id,
    	@i:=@i+1 as i,
    	@k:=(case when @score=a.sum_score then @k else @i end) as rank,
    	@score:=a.sum_score as score
    from (select s_id,SUM(s_score) as sum_score from score GROUP BY s_id ORDER BY sum_score DESC)a,
    	(select @k:=0,@i:=0,@score:=0)s
    	
    -- 21、查询不同老师所教不同课程平均分从高到低显示 
    		
    	select a.t_id,c.t_name,a.c_id,ROUND(avg(s_score),2) as avg_score from course a
    		left join score b on a.c_id=b.c_id 
    		left join teacher c on a.t_id=c.t_id
    		GROUP BY a.c_id,a.t_id,c.t_name ORDER BY avg_score DESC;
    -- 22、查询所有课程的成绩第2名到第3名的学生信息及该课程成绩
    			
    			select d.*,c.排名,c.s_score,c.c_id from (
                    select a.s_id,a.s_score,a.c_id,@i:=@i+1 as 排名 from score a,(select @i:=0)s where a.c_id='01'  
    								ORDER BY a.s_score DESC  
                )c
                left join student d on c.s_id=d.s_id
                where 排名 BETWEEN 2 AND 3
                UNION
                select d.*,c.排名,c.s_score,c.c_id from (
                    select a.s_id,a.s_score,a.c_id,@j:=@j+1 as 排名 from score a,(select @j:=0)s where a.c_id='02'  
    								ORDER BY a.s_score DESC
                )c
                left join student d on c.s_id=d.s_id
                where 排名 BETWEEN 2 AND 3
                UNION
                select d.*,c.排名,c.s_score,c.c_id from (
                    select a.s_id,a.s_score,a.c_id,@k:=@k+1 as 排名 from score a,(select @k:=0)s where a.c_id='03' 
    								ORDER BY a.s_score DESC
                )c
                left join student d on c.s_id=d.s_id
                where 排名 BETWEEN 2 AND 3;
    			
    -- 23、统计各科成绩各分数段人数:课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]及所占百分比
    
    
    		select distinct f.c_name,a.c_id,b.`85-100`,b.百分比,c.`70-85`,c.百分比,d.`60-70`,d.百分比,e.`0-60`,e.百分比 from score a
    				left join (select c_id,SUM(case when s_score >85 and s_score <=100 then 1 else 0 end) as `85-100`,
    											ROUND(100*(SUM(case when s_score >85 and s_score <=100 then 1 else 0 end)/count(*)),2) as 百分比
    								from score GROUP BY c_id)b on a.c_id=b.c_id
    				left join (select c_id,SUM(case when s_score >70 and s_score <=85 then 1 else 0 end) as `70-85`,
    											ROUND(100*(SUM(case when s_score >70 and s_score <=85 then 1 else 0 end)/count(*)),2) as 百分比
    								from score GROUP BY c_id)c on a.c_id=c.c_id
    				left join (select c_id,SUM(case when s_score >60 and s_score <=70 then 1 else 0 end) as `60-70`,
    											ROUND(100*(SUM(case when s_score >60 and s_score <=70 then 1 else 0 end)/count(*)),2) as 百分比
    								from score GROUP BY c_id)d on a.c_id=d.c_id
    				left join (select c_id,SUM(case when s_score >=0 and s_score <=60 then 1 else 0 end) as `0-60`,
    											ROUND(100*(SUM(case when s_score >=0 and s_score <=60 then 1 else 0 end)/count(*)),2) as 百分比
    								from score GROUP BY c_id)e on a.c_id=e.c_id
    				left join course f on a.c_id = f.c_id
    				 
    -- 24、查询学生平均成绩及其名次 
    
    		select a.s_id,
    				@i:=@i+1 as '不保留空缺排名',
    				@k:=(case when @avg_score=a.avg_s then @k else @i end) as '保留空缺排名',
    				@avg_score:=avg_s as '平均分'
    		from (select s_id,ROUND(AVG(s_score),2) as avg_s from score GROUP BY s_id ORDER BY avg_s DESC)a,(select @avg_score:=0,@i:=0,@k:=0)b;
    -- 25、查询各科成绩前三名的记录
    			-- 1.选出b表比a表成绩大的所有组
    			-- 2.选出比当前id成绩大的 小于三个的
    		select a.s_id,a.c_id,a.s_score from score a 
    			left join score b on a.c_id = b.c_id and a.s_score<b.s_score
    			group by a.s_id,a.c_id,a.s_score HAVING COUNT(b.s_id)<3
    			ORDER BY a.c_id,a.s_score DESC
    
    -- 26、查询每门课程被选修的学生数 
    
    		select c_id,count(s_id) from score a GROUP BY c_id
    
    -- 27、查询出只有两门课程的全部学生的学号和姓名 
    		select s_id,s_name from student where s_id in(
    				select s_id from score GROUP BY s_id HAVING COUNT(c_id)=2);
    
    -- 28、查询男生、女生人数 
    		select s_sex,COUNT(s_sex) as 人数  from student GROUP BY s_sex
    
    -- 29、查询名字中含有"风"字的学生信息
    
    		select * from student where s_name like '%风%';
    
    -- 30、查询同名同性学生名单,并统计同名人数 
    		
    		select a.s_name,a.s_sex,count(*) from student a  JOIN 
    					student b on a.s_id !=b.s_id and a.s_name = b.s_name and a.s_sex = b.s_sex
    		GROUP BY a.s_name,a.s_sex
    
    
    
    -- 31、查询1990年出生的学生名单
    		
    		select s_name from student where s_birth like '1990%'
    
    -- 32、查询每门课程的平均成绩,结果按平均成绩降序排列,平均成绩相同时,按课程编号升序排列 
    
    	select c_id,ROUND(AVG(s_score),2) as avg_score from score GROUP BY c_id ORDER BY avg_score DESC,c_id ASC
    
    -- 33、查询平均成绩大于等于85的所有学生的学号、姓名和平均成绩 
    
    	select a.s_id,b.s_name,ROUND(avg(a.s_score),2) as avg_score from score a
    		left join student b on a.s_id=b.s_id GROUP BY s_id HAVING avg_score>=85
    	
    -- 34、查询课程名称为"数学",且分数低于60的学生姓名和分数 
    	
    		select a.s_name,b.s_score from score b join student a on a.s_id=b.s_id where b.c_id=(
    					select c_id from course where c_name ='数学') and b.s_score<60
    
    -- 35、查询所有学生的课程及分数情况; 
    	
    		
    		select a.s_id,a.s_name,
    					SUM(case c.c_name when '语文' then b.s_score else 0 end) as '语文',
    					SUM(case c.c_name when '数学' then b.s_score else 0 end) as '数学',
    					SUM(case c.c_name when '英语' then b.s_score else 0 end) as '英语',
    					SUM(b.s_score) as  '总分'
    		from student a left join score b on a.s_id = b.s_id 
    		left join course c on b.c_id = c.c_id 
    		GROUP BY a.s_id,a.s_name
    
    
     -- 36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数; 
    			select a.s_name,b.c_name,c.s_score from course b left join score c on b.c_id = c.c_id
    				left join student a on a.s_id=c.s_id where c.s_score>=70
    
    		
    
    -- 37、查询不及格的课程
    		select a.s_id,a.c_id,b.c_name,a.s_score from score a left join course b on a.c_id = b.c_id
    			where a.s_score<60 
    		
    --38、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名; 
    		select a.s_id,b.s_name from score a LEFT JOIN student b on a.s_id = b.s_id
    			where a.c_id = '01'	and a.s_score>80
    
    -- 39、求每门课程的学生人数 
    		select count(*) from score GROUP BY c_id;
    
    -- 40、查询选修"张三"老师所授课程的学生中,成绩最高的学生信息及其成绩
    
    		
    		-- 查询老师id	
    		select c_id from course c,teacher d where c.t_id=d.t_id and d.t_name='张三'
    		-- 查询最高分(可能有相同分数)
    		select MAX(s_score) from score where c_id='02'
    		-- 查询信息
    		select a.*,b.s_score,b.c_id,c.c_name from student a
    			LEFT JOIN score b on a.s_id = b.s_id
    			LEFT JOIN course c on b.c_id=c.c_id
    			where b.c_id =(select c_id from course c,teacher d where c.t_id=d.t_id and d.t_name='张三')
    			and b.s_score in (select MAX(s_score) from score where c_id='02')
    
    
    -- 41、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩 
    	select DISTINCT b.s_id,b.c_id,b.s_score from score a,score b where a.c_id != b.c_id and a.s_score = b.s_score
    	
    
    -- 42、查询每门功成绩最好的前两名 
    		-- 牛逼的写法
    	select a.s_id,a.c_id,a.s_score from score a
    		where (select COUNT(1) from score b where b.c_id=a.c_id and b.s_score>=a.s_score)<=2 ORDER BY a.c_id
    
    
    -- 43、统计每门课程的学生选修人数(超过5人的课程才统计)。要求输出课程号和选修人数,查询结果按人数降序排列,若人数相同,按课程号升序排列  
    		select c_id,count(*) as total from score GROUP BY c_id HAVING total>5 ORDER BY total,c_id ASC
    		
    -- 44、检索至少选修两门课程的学生学号 
    		select s_id,count(*) as sel from score GROUP BY s_id HAVING sel>=2
    
    -- 45、查询选修了全部课程的学生信息 
    		select * from student where s_id in(		
    			select s_id from score GROUP BY s_id HAVING count(*)=(select count(*) from course))
    
    
    --46、查询各学生的年龄
    	-- 按照出生日期来算,当前月日 < 出生年月的月日则,年龄减一
    
    	select s_birth,(DATE_FORMAT(NOW(),'%Y')-DATE_FORMAT(s_birth,'%Y') - 
    				(case when DATE_FORMAT(NOW(),'%m%d')>DATE_FORMAT(s_birth,'%m%d') then 0 else 1 end)) as age
    		from student;
    
    
    -- 47、查询本周过生日的学生
    	select * from student where WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))=WEEK(s_birth)
    	select * from student where YEARWEEK(s_birth)=YEARWEEK(DATE_FORMAT(NOW(),'%Y%m%d'))
    	
    	select WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))
    
    -- 48、查询下周过生日的学生
    	select * from student where WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))+1 =WEEK(s_birth)
    
    -- 49、查询本月过生日的学生
    
    	select * from student where MONTH(DATE_FORMAT(NOW(),'%Y%m%d')) =MONTH(s_birth)
    	
    -- 50、查询下月过生日的学生
    	select * from student where MONTH(DATE_FORMAT(NOW(),'%Y%m%d'))+1 =MONTH(s_birth)
    
    
    展开全文
  • sql语句练习50题

    2019-02-28 19:59:34
    sql语句练习50题sql语句练习50题 Student(Sid,Sname,Sage,Ssex) 学生表 Course(Cid,Cname,Tid) 课程表 SC(Sid,Cid,score) 成绩表 Teacher(Tid,Tname) 教师表 练习内容: 1.查询“某1”课程比“某2”课程成绩高的...

    sql语句练习50题!


    sql语句练习50题

    Student(Sid,Sname,Sage,Ssex) 学生表
    Course(Cid,Cname,Tid) 课程表
    SC(Sid,Cid,score) 成绩表
    Teacher(Tid,Tname) 教师表

    练习内容:

    1.查询“某1”课程比“某2”课程成绩高的所有学生的学号;

    2.查询平均成绩大于60分的同学的学号和平均成绩;

    3.查询所有同学的学号、姓名、选课数、总成绩

    4.查询姓“李”的老师的个数;

    5.查询没学过“叶平”老师课的同学的学号、姓名;

    6.查询学过“”并且也学过编号“”课程的同学的学号、姓名;

    7.查询学过“叶平”老师所教的所有课的同学的学号、姓名;

    8.查询课程编号“”的成绩比课程编号“”课程低的所有同学的学号、姓名;

    9.查询所有课程成绩小于分的同学的学号、姓名;

    10.查询没有学全所有课的同学的学号、姓名;

    11.查询至少有一门课与学号为“”的同学所学相同的同学的学号和姓名;

    12.查询至少学过学号为“”同学所有一门课的其他同学学号和姓名;

    13.把“SC”表中“叶平”老师教的课的成绩都更改为此课程的平均成绩;

    14.查询和“”号的同学学习的课程完全相同的其他同学学号和姓名;

    15.删除学习“叶平”老师课的SC表记录;

    16.向SC表中插入一些记录,这些记录要求符合以下条件:没有上过编号“”课程的同学学号、课程的平均成绩;

    17.按平均成绩从高到低显示所有学生的“数据库”、“企业管理”、“英语”三门的课程成绩,按如下形式显示:学生ID,数据库,企业管理,英语,有效课程数,有效平均分;

    18.查询各科成绩最高和最低的分:以如下形式显示:课程ID,最高分,最低分;

    19.按各科平均成绩从低到高和及格率的百分数从高到低顺序

    26.查询每门课程被选修的学生数

    27.查询出只选修了一门课程的全部学生的学号和姓名

    32.查询每门课程的平均成绩,结果按平均成绩升序排列,平均成绩相同时,按课程号降序排列

    37.查询不及格的课程,并按课程号从大到小排列

    38.查询课程编号为且课程成绩在分以上的学生的学号和姓名;

    40.查询选修“叶平”老师所授课程的学生中,成绩最高的学生姓名及其成绩

    41.查询各个课程及相应的选修人数

    43.查询每门功成绩最好的前两名

    44.统计每门课程的学生选修人数(超过人的课程才统计)。要求输出课程号和选修人数,查询结果按人数降序排列,查询结果按人数降序排列,若人数相同,按课程号升序排列

    45.检索至少选修两门课程的学生学号
    rownum的用法
    查询所有成绩第二名到第四名的成绩

    47.查询没学过“叶平”老师讲授的任一门课程的学生姓名

    48.查询两门以上不及格课程的同学的学号及其平均成绩

    49.检索“”课程分数小于,按分数降序排列的同学学号

    50.删除“”同学的“”课程的成绩

    展开全文
  • SQL语句练习50题

    千次阅读 2019-05-13 17:58:13
    鉴于长时间不写sql语句,导致对sql有点遗弃,发现目前还是需要将sql捡起来,所以我从网上找来了这套题目,题目看着也还行,看了网上的这套的部分答案,很多都是基于结果来编写sql语句了,思想完全不对了,如果...

    前言

           鉴于长时间不写sql语句,导致对sql有点遗弃,发现目前还是需要将sql捡起来,所以我从网上找来了这套题目,题目看着也还行,看了网上的这套题的部分答案,很多都是基于结果来编写sql语句了,思想完全不对了,如果要是再多加几条数据,sql就完全没法用了,还是有一部分是错误的。

           诸如本题中的19题【按各科成绩进行排序,并显示排名】,分别对01课程,02课程,03课程排序,然后union在一起,这是什么个理啊?如果我加个04课程呢,感觉纯粹的糊弄人似的。

          这套题看着不错,所以我也拿来练练手,SQL都是纯手工练习敲写出来的,可能有部分语句是错误的,也希望大家能够帮我指正,谢谢大家。下面正式进入正题。


    表名和字段

    –1.学生表
         student(s_id,s_name,s_birth,s_sex) -- 学生编号,学生姓名, 出生年月,学生性别
    –2.课程表
         course(c_id,c_name,t_id) -- 课程编号, 课程名称, 教师编号
    –3.教师表
         teacher(t_id,t_name) -- 教师编号,教师姓名
    –4.成绩表
         score(s_id,c_id,s_score) -- 学生编号,课程编号,分数

    测试数据

    -- 建表
    -- 学生表
    CREATE TABLE `student`(
        `s_id` VARCHAR(20),
        `s_name` VARCHAR(20) NOT NULL DEFAULT '',
        `s_birth` VARCHAR(20) NOT NULL DEFAULT '',
        `s_sex` VARCHAR(10) NOT NULL DEFAULT '',
        PRIMARY KEY(`s_id`)
    );
    -- 课程表
    CREATE TABLE `course`(
        `c_id`  VARCHAR(20),
        `c_name` VARCHAR(20) NOT NULL DEFAULT '',
        `t_id` VARCHAR(20) NOT NULL,
        PRIMARY KEY(`c_id`)
    );
    -- 教师表
    CREATE TABLE `teacher`(
        `t_id` VARCHAR(20),
        `t_name` VARCHAR(20) NOT NULL DEFAULT '',
        PRIMARY KEY(`t_id`)
    );
    -- 成绩表
    CREATE TABLE `score`(
        `s_id` VARCHAR(20),
        `c_id`  VARCHAR(20),
        `s_score` INT(3),
        PRIMARY KEY(`s_id`,`c_id`)
    );
    -- 插入学生表测试数据
    insert into student values('01' , '赵雷' , '1990-01-01' , '男');
    insert into student values('02' , '钱电' , '1990-12-21' , '男');
    insert into student values('03' , '孙风' , '1990-05-20' , '男');
    insert into student values('04' , '李云' , '1990-08-06' , '男');
    insert into student values('05' , '周梅' , '1991-12-01' , '女');
    insert into student values('06' , '吴兰' , '1992-03-01' , '女');
    insert into student values('07' , '郑竹' , '1989-07-01' , '女');
    insert into student values('08' , '王菊' , '1990-01-20' , '女');
    insert into student values('01' , '赵雷' , '1992-08-09' , '男');
    -- 课程表测试数据
    insert into course values('01' , '语文' , '02');
    insert into course values('02' , '数学' , '01');
    insert into course values('03' , '英语' , '03');
    
    -- 教师表测试数据
    insert into teacher values('01' , '张三');
    insert into teacher values('02' , '李四');
    insert into teacher values('03' , '王五');
    
    -- 成绩表测试数据
    insert into score values('01' , '01' , 80);
    insert into score values('01' , '02' , 90);
    insert into score values('01' , '03' , 99);
    insert into score values('02' , '01' , 70);
    insert into score values('02' , '02' , 60);
    insert into score values('02' , '03' , 80);
    insert into score values('03' , '01' , 80);
    insert into score values('03' , '02' , 80);
    insert into score values('03' , '03' , 80);
    insert into score values('04' , '01' , 50);
    insert into score values('04' , '02' , 30);
    insert into score values('04' , '03' , 20);
    insert into score values('05' , '01' , 76);
    insert into score values('05' , '02' , 87);
    insert into score values('06' , '01' , 31);
    insert into score values('06' , '03' , 34);
    insert into score values('07' , '02' , 89);
    insert into score values('07' , '03' , 98);

    练习题和sql语句

    -- 1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数	
    select 
        s1.*,s2.s_score '课程01分数',s3.s_score '课程02分数'
    from 
        student s1
        inner join score s2 on s1.s_id = s2.s_id and s2.c_id = '01'
        inner join score s3 on s1.s_id = s3.s_id and s3.c_id = '02'
    where 
        s2.s_score > s3.s_score
    
    -- 2、查询"01"课程比"02"课程成绩低的学生的信息及课程分数
    select 
        s1.*,s2.s_score '课程01分数',s3.s_score '课程02分数'
    from 
        student s1
        inner join score s2 on s1.s_id = s2.s_id and s2.c_id = '01'
        inner join score s3 on s1.s_id = s3.s_id and s3.c_id = '02'
    where 
        s2.s_score < s3.s_score
    
    -- 3、查询平均成绩大于等于60分的同学的学生编号和学生姓名和平均成绩
    select
        s1.s_id,s1.s_name,round(avg(s2.s_score),2) avgGrade
    from 
        student s1
        left join score s2 on s1.s_id = s2.s_id
    group by
        s1.s_id,s1.s_name
    having
        avgGrade >= 60
    
    -- 4、查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩(包括有成绩的和无成绩的)
    select
        s1.s_id,s1.s_name,round(avg(s2.s_score),2) avgGrade
    from 
        student s1
        left join score s2 on s1.s_id = s2.s_id
    group by
        s1.s_id,s1.s_name
    having
        avgGrade < 60 or avgGrade is null
    		
    -- 5、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩
    select
        s1.s_id,s1.s_name,count(s2.c_id),sum(s2.s_score)
    from 
        student s1
        left join score s2 on s1.s_id = s2.s_id
    group by
        s1.s_id,s1.s_name
    	
    -- 6、查询"李"姓老师的数量 
    select
        count(t1.t_id)
    from
        teacher t1
    where 
        t1.t_name like '李%'  -- 此处为什么使用'李%',而不是'%李%',是因为考虑到了性能问题
    
    
    -- 7、查询学过"张三"老师授课的同学的信息 
    select
        s1.*
    from
        student s1
    where
        s1.s_id in (
            select
                sc1.s_id
            from 
                score sc1
            where
                sc1.c_id in(
                    select
                        c1.c_id
                    from
                        course c1
                    where
                        c1.t_id in(
                            select 
                                t1.t_id
                            from
                                teacher t1
                            where 
                                t1.t_name = '张三'
                        )
                )
        )
    
    -- 8、查询没学过"张三"老师授课的同学的信息 
    select
        s1.*
    from
        student s1
    where
        s1.s_id not in (
            select
                sc1.s_id
            from 
                score sc1
            where
                sc1.c_id in(
                    select
                        c1.c_id
                    from
                        course c1
                    where
                        c1.t_id in(
                            select 
                                t1.t_id
                            from
                                teacher t1
                            where 
                                t1.t_name = '张三'
                        )
                )
        )
    
    -- 9、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息
    select
        s1.*
    from
        student s1
    where
        s1.s_id in(
            select
                sc1.s_id
            from
                score sc1
            where
                sc1.c_id = '01' and sc1.s_id in (	
            select
                sc1.s_id
            from
                score sc1
            where
                sc1.c_id = '02')
        )
    
    -- 10、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
    select
        s1.*
    from
        student s1
    where
        s1.s_id in(
            select
                sc1.s_id
            from 
                score sc1
            where 
                sc1.c_id = '01'
        )
        and
        s1.s_id not in (
            select
                sc1.s_id
            from 
                score sc1
            where 
                sc1.c_id = '02'
        )
    
    -- 11、查询没有学全所有课程的同学的信息 
    select
        s1.*,count(s2.s_id)
    from
        student s1
        left join score s2 on s1.s_id = s2.s_id
    group by
        s2.s_id
    having
        count(s2.s_id) < (select count(1) from course)
    order by 
        s1.s_id
    
    -- 12、查询至少有一门课与学号为"01"的同学所学相同的同学的信息 
    select 
        s1.*
    from 
        student s1
    where 
        s1.s_id in(
            select distinct
                sr1.s_id
            from
                score sr1
            where
                sr1.c_id in(
                    select
                        sc1.s_id
                    from
                        score sc1
                    where 
                        sc1.c_id = '01'
                )
        )
    
    -- 13、查询和"01"号的同学学习的课程完全相同的其他同学的信息 
    继续研究中...待加入
    
    -- 14、查询没学过"张三"老师讲授的任一门课程的学生姓名 
    select 
        s1.s_name 
    from 
        student s1 
    where 
        s1.s_id in(
            select 
                s2.s_id
            from 
                score s2 
            where s2.c_id in (
                select 
                    cr1.c_id 
                from 
                    course cr1 
                where t_id = (
                    select 
                        t1.t_id 
                    from 
                        teacher t1 
                    where 
                        t1.t_name = '张三'
                )
            ) 
        )
    
    -- 15、查询两门及其以上不及格课程的同学的学号,姓名及其平均成绩
    select
        s1.s_id,s1.s_name,round(avg(s2.s_score),2)
    from
        student s1
        left join score s2 on s1.s_id = s2.s_id
    where
        s1.s_id in(
            select
                sr1.s_id
            from
                score sr1
            where
                sr1.s_score < 60
            group by
                sr1.s_id
            having 
                count(sr1.s_id) >= 2
        )
    group by
        s1.s_id
    
    -- 16、检索"01"课程分数小于60,按分数降序排列的学生信息
    select
        s1.*,s2.s_score
    from
        student s1
        left join score s2 on s1.s_id = s2.s_id
    where
        s2.c_id = '01' and s2.s_score < 60
    order by
        s2.s_score desc
    
    -- 17、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
    select
        s1.s_id,s1.s_name,s2.c_id,c1.c_name,s2.s_score,round(s4.avgGrade,2) avgPrice
    from
        student s1
        left join score s2 on s1.s_id = s2.s_id
        left join course c1 on s2.c_id = c1.c_id
        left join (select s3.s_id,avg(s3.s_score) avgGrade from score s3 group by s3.s_id) s4 on s1.s_id = s4.s_id
    group by
        s1.s_id,s1.s_name,s2.c_id,c1.c_name,s2.s_score
    order by 
        avgGrade desc
    	
    -- -----------------------------------------------------------
    -- (如下格式展示)id    名称    语文    数学    英语    平均分
    select 
        s1.s_id,s1.s_name,s2.s_score '语文',s3.s_score '数学',s4.s_score '英语',s5.avgPrice '平均分'
    from
        student s1
        left join (select s_id,s_score from score where c_id = '01') s2 on s1.s_id = s2.s_id
        left join (select s_id,s_score from score where c_id = '02') s3 on s1.s_id = s3.s_id
        left join (select s_id,s_score from score where c_id = '03') s4 on s1.s_id = s4.s_id
        left join (select s_id,round(avg(s_score),2) avgPrice from score group by s_id) s5 on s1.s_id = s5.s_id
    order by
        s5.avgPrice desc
    
    -- 18.查询各科成绩最高分、最低分和平均分:以如下形式显示:课程ID,课程name,最高分,最低分,平均分,及格率,中等率,优良率,优秀率
    -- 及格为>=60,中等为:70-80,优良为:80-90,优秀为:>=90
    select 
        sr1.c_id,c1.c_name,max(sr1.s_score) maxGrade,min(sr1.s_score) minGrade,avg(sr1.s_score) avgGrade,
        concat(ifnull(round(c3.jiGe/c2.total*100,2),'0.00'),'%') '及格率',
        concat(ifnull(round(c4.middle/c2.total*100,2),'0.00'),'%') '中等率',
        concat(ifnull(round(c5.youLiang/c2.total*100,2),'0.00'),'%') '优良率',
        concat(ifnull(round(c6.youXiu/c2.total*100,2),'0.00'),'%') '优秀率'
    from
        score sr1
        left join course c1 on sr1.c_id = c1.c_id
        left join (select sr2.c_id,count(sr2.s_score) total from score sr2 group by sr2.c_id) c2 on sr1.c_id = c2.c_id
        left join (select sr3.c_id,count(sr3.s_score) jiGe from score sr3 where sr3.s_score >=60 group by sr3.c_id) c3 on sr1.c_id = c3.c_id
        left join (select sr4.c_id,count(sr4.s_score) middle from score sr4 where sr4.s_score >=70 and sr4.s_score <80 group by sr4.c_id) c4 on sr1.c_id = c4.c_id
        left join (select sr5.c_id,count(sr5.s_score) youLiang from score sr5 where sr5.s_score >=80 and sr5.s_score <90 group by sr5.c_id) c5 on sr1.c_id = c5.c_id
        left join (select sr6.c_id,count(sr6.s_score) youXiu from score sr6 where sr6.s_score >=90 group by sr6.c_id) c6 on sr1.c_id = c6.c_id
    group by
        sr1.c_id,c1.c_name
    
    -- 19、按各科成绩进行排序,并显示排名
    -- 分组普通排名:顺序排名
    select 
        s_id,c_id,s_score,rank
    from(
        select
            s1.*,IF(@p=s1.c_id,@r:=@r+1,@r:=1) AS rank,@p:=s1.c_id
        from
            score s1,(SELECT @p:=NULL,@r:=0)r
        order by
            s1.c_id,s1.s_score desc
    ) s
    	
    -- 分组后并列排名:组内相同数值排名相同
    select 
        s_id,c_id,s_score,rank
    from(
        select *,
            if(@p=s1.c_id,
                case 
                    when @s=s1.s_score then @r
                    when @s:=s1.s_score then @r:=@r+1
                end,
            @r:=1 ) as rank,
            @p:=s1.c_id,
            @s:=s1.s_score
        from 
            score s1,(select @p:=NULL,@s:=NULL,@r:=0)r
        order by 
            s1.c_id,s1.s_score desc 
    )s
    
    
    -- 20、查询学生的总成绩并进行排名
    select
        tb.*,@rank:=@rank+1 rank
    from(
        select
            s1.s_id,s1.s_name,sum(s2.s_score) grades
        from
            student s1
            left join score s2 on s1.s_id = s2.s_id
        group by
            s1.s_id,s1.s_name
        order by
            grades desc
    ) tb,(select @rank:=0) rank
    
    
    -- 21、查询不同老师所教不同课程平均分从高到低显示 
    select
        t1.t_id,t1.t_name,s1.c_id,round(avg(s1.s_score),2) avgGrade
    from
        teacher t1
        left join course c1 on t1.t_id = c1.t_id
        left join score s1 on c1.c_id = s1.c_id
    group by 
        s1.c_id,t1.t_id,t1.t_name
    order by
        avgGrade desc
    
    -- 22、查询所有课程的成绩第2名到第3名的学生信息及该课程成绩
    select 
        s.s_id,s1.s_name,s.c_id,c1.c_name,s.s_score,s.rank
    from(
        select
            s1.*,IF(@p=s1.c_id,@r:=@r+1,@r:=1) AS rank,@p:=s1.c_id
        from
            score s1,(SELECT @p:=NULL,@r:=0)r
        order by 
            s1.c_id,s1.s_score desc
    ) s left join student s1 on s.s_id = s1.s_id
        left join course c1 on s.c_id = c1.c_id
    where 
        s.rank >=2 and s.rank <=3
    
    -- 23、统计各科成绩各分数段人数:课程编号,课程名称,[85-100],[70-85),[60-70),[0-60)及所占百分比
    select
        c1.c_id,
        c1.c_name,
        ifnull(c2.nums,0) as '[85-100]人数',
        concat(round(ifnull(c2.nums,0)/c2.total*100,2),'%') '[85-100]占比',
        ifnull(c3.nums,0) as '[70-85)人数',
        concat(round(ifnull(c3.nums,0)/c3.total*100,2),'%') '[70-85)占比',
        ifnull(c4.nums,0) as '[60-70)人数',
        concat(round(ifnull(c4.nums,0)/c4.total*100,2),'%') '[60-75)占比',
        ifnull(c5.nums,0) as '[0-60)人数',
        concat(round(ifnull(c5.nums,0)/c5.total*100,2),'%') '[0-60)占比'
    from
        course c1
        left join(
            select 
                s1.c_id,
                s2.nums,
                count(s1.s_id) total 
            from 
                score s1 
                left join (
                    select 
                        sc1.c_id,
                        count(sc1.s_id) nums 
                    from
                        score sc1 
                    where 
                        sc1.s_score >= 85
                    group by 
                        sc1.c_id
                ) s2 on s1.c_id = s2.c_id
             group by s1.c_id
        ) c2 on c1.c_id = c2.c_id    -- 下面三个同上面,所以没有一一展开
        left join(select s1.c_id,s3.nums,count(s1.s_id) total from score s1 left join (select sc1.c_id,count(sc1.s_id) nums from score sc1 where sc1.s_score >= 70 and sc1.s_score < 85 group by sc1.c_id) s3 on s1.c_id = s3.c_id group by s1.c_id) c3 on c1.c_id = c3.c_id
        left join(select s1.c_id,s4.nums,count(s1.s_id) total from score s1 left join (select sc1.c_id,count(sc1.s_id) nums from score sc1 where sc1.s_score >= 60 and sc1.s_score < 70 group by sc1.c_id) s4 on s1.c_id = s4.c_id group by s1.c_id) c4 on c1.c_id = c4.c_id
        left join(select s1.c_id,s5.nums,count(s1.s_id) total from score s1 left join (select sc1.c_id,count(sc1.s_id) nums from score sc1 where sc1.s_score < 60 group by sc1.c_id) s5 on s1.c_id = s5.c_id group by s1.c_id) c5 on c1.c_id = c5.c_id
    
    -- 24、查询学生平均成绩及其名次 
    select 
        tb1.*,@r:=@r+1 rank
    from(
        select
            s1.s_id,
            s1.s_name,
            ifnull(round(avg(s2.s_score),2),0) avgGrade
        from
            student s1
            left join score s2 on s1.s_id = s2.s_id
        group by 
            s1.s_id
        order by 
            avgGrade desc
    ) tb1,(select @r:=0) tb2
    
    -- 25、查询各科成绩前三名的记录
    select 
        s.s_id,s1.s_name,c1.c_name,s.s_score,s.rank
    from(
        select
            s1.*,IF(@p=s1.c_id,@r:=@r+1,@r:=1) AS rank,@p:=s1.c_id
        from
            score s1,(SELECT @p:=NULL,@r:=0)r
        order by 
            s1.c_id,
            s1.s_score desc
    ) s left join student s1 on s.s_id = s1.s_id
        left join course c1 on s.c_id = c1.c_id
    where 
        s.rank <=3
    			
    -- 26、查询每门课程被选修的学生数 
    select
        c1.c_id,c1.c_name,count(s1.s_id) nums
    from
        course c1
        left join score s1 on c1.c_id = s1.c_id
    group by
        s1.c_id
    
    -- 27、查询出只有两门课程的全部学生的学号和姓名 
    select
        s1.s_id,
        s1.s_name
    from 
        student s1
        left join score s2 on s1.s_id = s2.s_id
    group by
        s1.s_id,
        s1.s_name
    having
        count(s2.c_id) = 2
    
    -- 28、查询男生、女生人数 
    select
        s1.s_sex '性别',count(s1.s_sex) '人数'
    from 
        student s1
    group by
        s1.s_sex
    
    -- 29、查询名字中含有"风"字的学生信息
    select
        s1.*
    from
        student s1
    where
        s1.s_name like '%风%'
    
    
    -- 30、查询同名同性别学生名单,并统计同名人数 
    select distinct
        s1.s_name '姓名',
        count(s1.s_name) '人数'
    from
        student s1
        join student s2 on s1.s_name = s2.s_name and s1.s_sex = s2.s_sex and s1.s_id <> s2.s_id
    
    -- 31、查询1990年出生的学生名单(如下:四选一)
    select s1.* from student s1 where date_format(s1.s_birth,'%Y') = '1990'
    select s1.* from student s1 where left(s1.s_birth,4) = '1990'
    select s1.* from student s1 where substring(s1.s_birth,1,4) = '1990'
    select s1.* from student s1 where s1.s_birth like '1990%'
    
    -- 32、查询每门课程的平均成绩,结果按平均成绩降序排列,平均成绩相同时,按课程编号升序排列 
    select
        c1.c_id,
        c1.c_name,
        round(avg(s1.s_score),2) avgGrade
    from
        course c1
        left join score s1 on c1.c_id = s1.c_id 
    group by
        c1.c_id,c1.c_name
    order by
        avgGrade desc,
        c1.c_id asc
    
    -- 33、查询平均成绩大于等于85的所有学生的学号、姓名和平均成绩 
    select
        s1.s_id,
        s1.s_name,
        round(avg(s2.s_score),2) avgGrade
    from
        student s1
        left join score s2 on s1.s_id = s2.s_id
    group by
        s1.s_id
    having
        avgGrade >= 85
    
    -- 34、查询课程名称为"数学",且分数低于60的学生姓名和分数 
    select
        s1.s_name,
        s2.s_score
    from
        student s1
        left join score s2 on s1.s_id = s2.s_id
        left join course c1 on s2.c_id = c1.c_id
    where
        c1.c_name = '数学'
        and s2.s_score < 60
    
    -- 35、查询所有学生的课程及分数情况; 
    select 
        s1.s_id,
        s1.s_name,
        c1.c_name,
        s2.s_score
    from
        student s1 
        left join score s2 on s1.s_id = s2.s_id 
        left join course c1 on s2.c_id = c1.c_id
    
    -- 36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数; 
    select 
        s1.s_name,c1.c_name,s2.s_score
    from 
        student s1
        left join score s2 on s1.s_id = s2.s_id
        left join course c1 on s2.c_id = c1.c_id
    where
        s2.s_score >70
    
    -- 37、查询不及格的课程(和36一样,没意义)
    select 
        s1.s_name,c1.c_name,s2.s_score
    from 
        student s1
        left join score s2 on s1.s_id = s2.s_id
        left join course c1 on s2.c_id = c1.c_id
    where
        s2.s_score < 60
    
    -- 38、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名;
    select 
        s1.s_id,
        s1.s_name
    from
        student s1
        left join score s2 on s1.s_id = s2.s_id
        left join course c1 on s2.c_id = c1.c_id
    where
        c1.c_id = '01' 
        and s2.s_score >= 80
    
    -- 39、求每门课程的学生人数 
    select
        c1.c_id,
        c1.c_name,
        count(1) nums
    from 
        course c1 
        left join score s1 on c1.c_id = s1.c_id
    group by
        c1.c_id,
        c1.c_name
    
    
    -- 40、查询选修"张三"老师所授课程的学生中,成绩最高的学生信息及其成绩
    select
        s1.*,
        s2.s_score
    from 
        student s1
        left join score s2 on s1.s_id = s2.s_id
    where 
        s2.c_id = (
            select 
                c1.c_id 
            from 
                teacher t1 
                left join course c1 on t1.t_id = c1.t_id 
            where 
                t1.t_name = '张三'
        ) and s2.s_score = (
            select 
                max(s1.s_score) 
            from 
                score s1 
            where s1.c_id in (
                select 
                    c1.c_id 
                from 
                    teacher t1 
                    left join course c1 on t1.t_id = c1.t_id 
                where 
                    t1.t_name = '张三')
        )
    
    -- 41、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩(出题者,出这题有什么意义?看不懂...)
    select distinct
        s1.s_id,
        s1.c_id,
        s1.s_score
    from
        score s1 
        join score s2 on s1.s_score = s2.s_score and s1.c_id != s2.c_id
    
    -- 42、查询每门功成绩最好的前两名(重复题,与22,25没区别)
    select 
        s.s_id,s1.s_name,s.c_id,c1.c_name,s.s_score,s.rank
    from(
        select
            s1.*,IF(@p=s1.c_id,@r:=@r+1,@r:=1) AS rank,@p:=s1.c_id
        from
            score s1,(SELECT @p:=NULL,@r:=0)r
        order by 
            s1.c_id,s1.s_score desc
    ) s left join student s1 on s.s_id = s1.s_id
        left join course c1 on s.c_id = c1.c_id
    where 
        s.rank <=2 
    
    -- 43、统计每门课程的学生选修人数(超过5人的课程才统计)。要求输出课程号和选修人数,查询结果按人数降序排列,若人数相同,按课程号升序排列  
    select
        s1.c_id ,count(1) nums
    from
        score s1
    group by 
        s1.c_id
    having
        nums > 5
    order by
        nums desc,
        s1.c_id asc
    
    -- 44、检索至少选修两门课程的学生学号 
    select
        s1.s_id
    from
        score s1
    group by
        s1.s_id
    having 
        count(s1.c_id) >= 2
    
    -- 45、查询选修了全部课程的学生信息 
    select
        s1.s_id,
        s1.s_name,
        count(s2.s_id) total
    from
        student s1
        left join score s2 on s1.s_id = s2.s_id
    group by
        s1.s_id,
        s1.s_name
    having
        total = (select count(1) from course)
    
    -- 46、查询各学生的年龄
    	-- 按照出生日期来算,当前月日 < 出生年月的月日则,年龄减一
    select
        s1.s_id,
        s1.s_name,
        DATE_FORMAT(now(),'%Y') - DATE_FORMAT(s1.s_birth,'%Y') - (case when DATE_FORMAT(NOW(),'%m%d')>DATE_FORMAT(s_birth,'%m%d') then 0 else 1 end) age
    from
        student s1
    	
    -- 47、查询本周过生日的学生
    select
        s1.s_id,s1.s_name
    from
        student s1
    where
        WEEK(now()) = WEEK(s1.s_birth)
    
    -- 48、查询下周过生日的学生
    select
        s1.s_id,s1.s_name
    from
        student s1
    where
        WEEK(now()) + 1 = WEEK(s1.s_birth)
    
    -- 49、查询本月过生日的学生
    select
        s1.s_id,s1.s_name
    from
        student s1
    where
        MONTH(now()) = MONTH(s1.s_birth)
    
    -- 50、查询下月过生日的学生
    select
        s1.s_id,s1.s_name
    from
        student s1
    where
        MONTH(now()) + 1 = MONTH(s1.s_birth)

     

     

     

     

     

     

     

     

     

    展开全文
  • MySQL经典练习题及答案,常用SQL语句练习50题

    万次阅读 多人点赞 2018-05-21 15:45:33
    练习题sql语句 -- 1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数 select a.* ,b.s_score as 01 _score,c.s_score as 02 _score from student a join score b on a.s_id=b.s_id ...

    表名和字段

    –1.学生表 
    Student(s_id,s_name,s_birth,s_sex) –学生编号,学生姓名, 出生年月,学生性别 
    –2.课程表 
    Course(c_id,c_name,t_id) – –课程编号, 课程名称, 教师编号 
    –3.教师表 
    Teacher(t_id,t_name) –教师编号,教师姓名 
    –4.成绩表 
    Score(s_id,c_id,s_score) –学生编号,课程编号,分数

    测试数据

    --建表
    --学生表
    CREATE TABLE `Student`(
        `s_id` VARCHAR(20),
        `s_name` VARCHAR(20) NOT NULL DEFAULT '',
        `s_birth` VARCHAR(20) NOT NULL DEFAULT '',
        `s_sex` VARCHAR(10) NOT NULL DEFAULT '',
        PRIMARY KEY(`s_id`)
    );
    --课程表
    CREATE TABLE `Course`(
        `c_id`  VARCHAR(20),
        `c_name` VARCHAR(20) NOT NULL DEFAULT '',
        `t_id` VARCHAR(20) NOT NULL,
        PRIMARY KEY(`c_id`)
    );
    --教师表
    CREATE TABLE `Teacher`(
        `t_id` VARCHAR(20),
        `t_name` VARCHAR(20) NOT NULL DEFAULT '',
        PRIMARY KEY(`t_id`)
    );
    --成绩表
    CREATE TABLE `Score`(
        `s_id` VARCHAR(20),
        `c_id`  VARCHAR(20),
        `s_score` INT(3),
        PRIMARY KEY(`s_id`,`c_id`)
    );
    --插入学生表测试数据
    insert into Student values('01' , '赵雷' , '1990-01-01' , '男');
    insert into Student values('02' , '钱电' , '1990-12-21' , '男');
    insert into Student values('03' , '孙风' , '1990-05-20' , '男');
    insert into Student values('04' , '李云' , '1990-08-06' , '男');
    insert into Student values('05' , '周梅' , '1991-12-01' , '女');
    insert into Student values('06' , '吴兰' , '1992-03-01' , '女');
    insert into Student values('07' , '郑竹' , '1989-07-01' , '女');
    insert into Student values('08' , '王菊' , '1990-01-20' , '女');
    --课程表测试数据
    insert into Course values('01' , '语文' , '02');
    insert into Course values('02' , '数学' , '01');
    insert into Course values('03' , '英语' , '03');
    
    --教师表测试数据
    insert into Teacher values('01' , '张三');
    insert into Teacher values('02' , '李四');
    insert into Teacher values('03' , '王五');
    
    --成绩表测试数据
    insert into Score values('01' , '01' , 80);
    insert into Score values('01' , '02' , 90);
    insert into Score values('01' , '03' , 99);
    insert into Score values('02' , '01' , 70);
    insert into Score values('02' , '02' , 60);
    insert into Score values('02' , '03' , 80);
    insert into Score values('03' , '01' , 80);
    insert into Score values('03' , '02' , 80);
    insert into Score values('03' , '03' , 80);
    insert into Score values('04' , '01' , 50);
    insert into Score values('04' , '02' , 30);
    insert into Score values('04' , '03' , 20);
    insert into Score values('05' , '01' , 76);
    insert into Score values('05' , '02' , 87);
    insert into Score values('06' , '01' , 31);
    insert into Score values('06' , '03' , 34);
    insert into Score values('07' , '02' , 89);
    insert into Score values('07' , '03' , 98);

    练习题和sql语句

    -- 1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数  
    
    select a.* ,b.s_score as 01_score,c.s_score as 02_score from 
        student a 
        join score b on a.s_id=b.s_id and b.c_id='01'
        left join score c on a.s_id=c.s_id and c.c_id='02' or c.c_id = NULL where b.s_score>c.s_score
    
    
    -- 2、查询"01"课程比"02"课程成绩低的学生的信息及课程分数
    
    select a.* ,b.s_score as 01_score,c.s_score as 02_score from 
        student a left join score b on a.s_id=b.s_id and b.c_id='01' or b.c_id=NULL 
         join score c on a.s_id=c.s_id and c.c_id='02' where b.s_score<c.s_score
    
    
    -- 3、查询平均成绩大于等于60分的同学的学生编号和学生姓名和平均成绩
    select b.s_id,b.s_name,ROUND(AVG(a.s_score),2) as avg_score from 
        student b 
        join score a on b.s_id = a.s_id
        GROUP BY b.s_id,b.s_name HAVING ROUND(AVG(a.s_score),2)>=60;
    
    
    -- 4、查询平均成绩小于60分的同学的学生编号和学生姓名和平均成绩
            -- (包括有成绩的和无成绩的)
    
    select b.s_id,b.s_name,ROUND(AVG(a.s_score),2) as avg_score from 
        student b 
        left join score a on b.s_id = a.s_id
        GROUP BY b.s_id,b.s_name HAVING ROUND(AVG(a.s_score),2)<60
        union
    select a.s_id,a.s_name,0 as avg_score from 
        student a 
        where a.s_id not in (
                    select distinct s_id from score);
    
    
    -- 5、查询所有同学的学生编号、学生姓名、选课总数、所有课程的总成绩
    select a.s_id,a.s_name,count(b.c_id) as sum_course,sum(b.s_score) as sum_score from 
        student a 
        left join score b on a.s_id=b.s_id
        GROUP BY a.s_id,a.s_name;
    
    
    -- 6、查询"李"姓老师的数量 
    select count(t_id) from teacher where t_name like '李%';
    
    -- 7、查询学过"张三"老师授课的同学的信息 
    select a.* from 
        student a 
        join score b on a.s_id=b.s_id where b.c_id in(
            select c_id from course where t_id =(
                select t_id from teacher where t_name = '张三'));
    
    -- 8、查询没学过"张三"老师授课的同学的信息 
    select * from 
        student c 
        where c.s_id not in(
            select a.s_id from student a join score b on a.s_id=b.s_id where b.c_id in(
                select c_id from course where t_id =(
                    select t_id from teacher where t_name = '张三')));
    -- 9、查询学过编号为"01"并且也学过编号为"02"的课程的同学的信息
    
    select a.* from 
        student a,score b,score c 
        where a.s_id = b.s_id  and a.s_id = c.s_id and b.c_id='01' and c.c_id='02';
    
    -- 10、查询学过编号为"01"但是没有学过编号为"02"的课程的同学的信息
    
    select a.* from 
        student a 
        where a.s_id in (select s_id from score where c_id='01' ) and a.s_id not in(select s_id from score where c_id='02')
    
    
    -- 11、查询没有学全所有课程的同学的信息 
    
    select s.* from 
        student s where s.s_id in(
            select s_id from score where s_id not in(
                select a.s_id from score a 
                    join score b on a.s_id = b.s_id and b.c_id='02'
                    join score c on a.s_id = c.s_id and c.c_id='03'
                where a.c_id='01'))
    
    -- 12、查询至少有一门课与学号为"01"的同学所学相同的同学的信息 
    
    select * from student where s_id in(
        select distinct a.s_id from score a where a.c_id in(select a.c_id from score a where a.s_id='01')
        );
    
    -- 13、查询和"01"号的同学学习的课程完全相同的其他同学的信息 
    
    select a.* from student a where a.s_id in(
        select distinct s_id from score where s_id!='01' and c_id in(select c_id from score where s_id='01')
        group by s_id 
        having count(1)=(select count(1) from score where s_id='01'));
    -- 14、查询没学过"张三"老师讲授的任一门课程的学生姓名 
    select a.s_name from student a where a.s_id not in (
        select s_id from score where c_id = 
                    (select c_id from course where t_id =(
                        select t_id from teacher where t_name = '张三')) 
                    group by s_id);
    
    -- 15、查询两门及其以上不及格课程的同学的学号,姓名及其平均成绩 
    select a.s_id,a.s_name,ROUND(AVG(b.s_score)) from 
        student a 
        left join score b on a.s_id = b.s_id
        where a.s_id in(
                select s_id from score where s_score<60 GROUP BY  s_id having count(1)>=2)
        GROUP BY a.s_id,a.s_name
    
    -- 16、检索"01"课程分数小于60,按分数降序排列的学生信息
    select a.*,b.c_id,b.s_score from 
        student a,score b 
        where a.s_id = b.s_id and b.c_id='01' and b.s_score<60 ORDER BY b.s_score DESC;
    
    -- 17、按平均成绩从高到低显示所有学生的所有课程的成绩以及平均成绩
    select a.s_id,(select s_score from score where s_id=a.s_id and c_id='01') as 语文,
                    (select s_score from score where s_id=a.s_id and c_id='02') as 数学,
                    (select s_score from score where s_id=a.s_id and c_id='03') as 英语,
                round(avg(s_score),2) as 平均分 from score a  GROUP BY a.s_id ORDER BY 平均分 DESC;
    
    -- 18.查询各科成绩最高分、最低分和平均分:以如下形式显示:课程ID,课程name,最高分,最低分,平均分,及格率,中等率,优良率,优秀率
    --及格为>=60,中等为:70-80,优良为:80-90,优秀为:>=90
    select a.c_id,b.c_name,MAX(s_score),MIN(s_score),ROUND(AVG(s_score),2),
        ROUND(100*(SUM(case when a.s_score>=60 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 及格率,
        ROUND(100*(SUM(case when a.s_score>=70 and a.s_score<=80 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 中等率,
        ROUND(100*(SUM(case when a.s_score>=80 and a.s_score<=90 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 优良率,
        ROUND(100*(SUM(case when a.s_score>=90 then 1 else 0 end)/SUM(case when a.s_score then 1 else 0 end)),2) as 优秀率
        from score a left join course b on a.c_id = b.c_id GROUP BY a.c_id,b.c_name
    
    -- 19、按各科成绩进行排序,并显示排名(实现不完全)
    -- mysql没有rank函数
        select a.s_id,a.c_id,
            @i:=@i +1 as i保留排名,
            @k:=(case when @score=a.s_score then @k else @i end) as rank不保留排名,
            @score:=a.s_score as score
        from (
            select s_id,c_id,s_score from score WHERE c_id='01' GROUP BY s_id,c_id,s_score ORDER BY s_score DESC
    )a,(select @k:=0,@i:=0,@score:=0)s
        union
        select a.s_id,a.c_id,
            @i:=@i +1 as i,
            @k:=(case when @score=a.s_score then @k else @i end) as rank,
            @score:=a.s_score as score
        from (
            select s_id,c_id,s_score from score WHERE c_id='02' GROUP BY s_id,c_id,s_score ORDER BY s_score DESC
    )a,(select @k:=0,@i:=0,@score:=0)s
        union
        select a.s_id,a.c_id,
            @i:=@i +1 as i,
            @k:=(case when @score=a.s_score then @k else @i end) as rank,
            @score:=a.s_score as score
        from (
            select s_id,c_id,s_score from score WHERE c_id='03' GROUP BY s_id,c_id,s_score ORDER BY s_score DESC
    )a,(select @k:=0,@i:=0,@score:=0)s
    
    -- 20、查询学生的总成绩并进行排名
    select a.s_id,
        @i:=@i+1 as i,
        @k:=(case when @score=a.sum_score then @k else @i end) as rank,
        @score:=a.sum_score as score
    from (select s_id,SUM(s_score) as sum_score from score GROUP BY s_id ORDER BY sum_score DESC)a,
        (select @k:=0,@i:=0,@score:=0)s
    
    -- 21、查询不同老师所教不同课程平均分从高到低显示 
    
        select a.t_id,c.t_name,a.c_id,ROUND(avg(s_score),2) as avg_score from course a
            left join score b on a.c_id=b.c_id 
            left join teacher c on a.t_id=c.t_id
            GROUP BY a.c_id,a.t_id,c.t_name ORDER BY avg_score DESC;
    -- 22、查询所有课程的成绩第2名到第3名的学生信息及该课程成绩
    
                select d.*,c.排名,c.s_score,c.c_id from (
                    select a.s_id,a.s_score,a.c_id,@i:=@i+1 as 排名 from score a,(select @i:=0)s where a.c_id='01'    
                )c
                left join student d on c.s_id=d.s_id
                where 排名 BETWEEN 2 AND 3
                UNION
                select d.*,c.排名,c.s_score,c.c_id from (
                    select a.s_id,a.s_score,a.c_id,@j:=@j+1 as 排名 from score a,(select @j:=0)s where a.c_id='02'    
                )c
                left join student d on c.s_id=d.s_id
                where 排名 BETWEEN 2 AND 3
                UNION
                select d.*,c.排名,c.s_score,c.c_id from (
                    select a.s_id,a.s_score,a.c_id,@k:=@k+1 as 排名 from score a,(select @k:=0)s where a.c_id='03'    
                )c
                left join student d on c.s_id=d.s_id
                where 排名 BETWEEN 2 AND 3;
    
    
    -- 23、统计各科成绩各分数段人数:课程编号,课程名称,[100-85],[85-70],[70-60],[0-60]及所占百分比
    
    
            select distinct f.c_name,a.c_id,b.`85-100`,b.百分比,c.`70-85`,c.百分比,d.`60-70`,d.百分比,e.`0-60`,e.百分比 from score a
                    left join (select c_id,SUM(case when s_score >85 and s_score <=100 then 1 else 0 end) as `85-100`,
                                                ROUND(100*(SUM(case when s_score >85 and s_score <=100 then 1 else 0 end)/count(*)),2) as 百分比
                                    from score GROUP BY c_id)b on a.c_id=b.c_id
                    left join (select c_id,SUM(case when s_score >70 and s_score <=85 then 1 else 0 end) as `70-85`,
                                                ROUND(100*(SUM(case when s_score >70 and s_score <=85 then 1 else 0 end)/count(*)),2) as 百分比
                                    from score GROUP BY c_id)c on a.c_id=c.c_id
                    left join (select c_id,SUM(case when s_score >60 and s_score <=70 then 1 else 0 end) as `60-70`,
                                                ROUND(100*(SUM(case when s_score >60 and s_score <=70 then 1 else 0 end)/count(*)),2) as 百分比
                                    from score GROUP BY c_id)d on a.c_id=d.c_id
                    left join (select c_id,SUM(case when s_score >=0 and s_score <=60 then 1 else 0 end) as `0-60`,
                                                ROUND(100*(SUM(case when s_score >=0 and s_score <=60 then 1 else 0 end)/count(*)),2) as 百分比
                                    from score GROUP BY c_id)e on a.c_id=e.c_id
                    left join course f on a.c_id = f.c_id
    
    -- 24、查询学生平均成绩及其名次 
    
            select a.s_id,
                    @i:=@i+1 as '不保留空缺排名',
                    @k:=(case when @avg_score=a.avg_s then @k else @i end) as '保留空缺排名',
                    @avg_score:=avg_s as '平均分'
            from (select s_id,ROUND(AVG(s_score),2) as avg_s from score GROUP BY s_id)a,(select @avg_score:=0,@i:=0,@k:=0)b;
    -- 25、查询各科成绩前三名的记录
                -- 1.选出b表比a表成绩大的所有组
                -- 2.选出比当前id成绩大的 小于三个的
            select a.s_id,a.c_id,a.s_score from score a 
                left join score b on a.c_id = b.c_id and a.s_score<b.s_score
                group by a.s_id,a.c_id,a.s_score HAVING COUNT(b.s_id)<3
                ORDER BY a.c_id,a.s_score DESC
    
    -- 26、查询每门课程被选修的学生数 
    
            select c_id,count(s_id) from score a GROUP BY c_id
    
    -- 27、查询出只有两门课程的全部学生的学号和姓名 
            select s_id,s_name from student where s_id in(
                    select s_id from score GROUP BY s_id HAVING COUNT(c_id)=2);
    
    -- 28、查询男生、女生人数 
            select s_sex,COUNT(s_sex) as 人数  from student GROUP BY s_sex
    
    -- 29、查询名字中含有"风"字的学生信息
    
            select * from student where s_name like '%风%';
    
    -- 30、查询同名同性学生名单,并统计同名人数 
    
            select a.s_name,a.s_sex,count(*) from student a  JOIN 
                        student b on a.s_id !=b.s_id and a.s_name = b.s_name and a.s_sex = b.s_sex
            GROUP BY a.s_name,a.s_sex
    
    
    
    -- 31、查询1990年出生的学生名单
    
            select s_name from student where s_birth like '1990%'
    
    -- 32、查询每门课程的平均成绩,结果按平均成绩降序排列,平均成绩相同时,按课程编号升序排列 
    
        select c_id,ROUND(AVG(s_score),2) as avg_score from score GROUP BY c_id ORDER BY avg_score DESC,c_id ASC
    
    -- 33、查询平均成绩大于等于85的所有学生的学号、姓名和平均成绩 
    
        select a.s_id,b.s_name,ROUND(avg(a.s_score),2) as avg_score from score a
            left join student b on a.s_id=b.s_id GROUP BY s_id HAVING avg_score>=85
    
    -- 34、查询课程名称为"数学",且分数低于60的学生姓名和分数 
    
            select a.s_name,b.s_score from score b LEFT JOIN student a on a.s_id=b.s_id where b.c_id=(
                        select c_id from course where c_name ='数学') and b.s_score<60
    
    -- 35、查询所有学生的课程及分数情况; 
    
    
            select a.s_id,a.s_name,
                        SUM(case c.c_name when '语文' then b.s_score else 0 end) as '语文',
                        SUM(case c.c_name when '数学' then b.s_score else 0 end) as '数学',
                        SUM(case c.c_name when '英语' then b.s_score else 0 end) as '英语',
                        SUM(b.s_score) as  '总分'
            from student a left join score b on a.s_id = b.s_id 
            left join course c on b.c_id = c.c_id 
            GROUP BY a.s_id,a.s_name
    
    
     -- 36、查询任何一门课程成绩在70分以上的姓名、课程名称和分数; 
                select a.s_name,b.c_name,c.s_score from course b left join score c on b.c_id = c.c_id
                    left join student a on a.s_id=c.s_id where c.s_score>=70
    
    
    
    -- 37、查询不及格的课程
            select a.s_id,a.c_id,b.c_name,a.s_score from score a left join course b on a.c_id = b.c_id
                where a.s_score<60 
    
    --38、查询课程编号为01且课程成绩在80分以上的学生的学号和姓名; 
            select a.s_id,b.s_name from score a LEFT JOIN student b on a.s_id = b.s_id
                where a.c_id = '01' and a.s_score>80
    
    -- 39、求每门课程的学生人数 
            select count(*) from score GROUP BY c_id;
    
    -- 40、查询选修"张三"老师所授课程的学生中,成绩最高的学生信息及其成绩
    
    
            -- 查询老师id   
            select c_id from course c,teacher d where c.t_id=d.t_id and d.t_name='张三'
            -- 查询最高分(可能有相同分数)
            select MAX(s_score) from score where c_id='02'
            -- 查询信息
            select a.*,b.s_score,b.c_id,c.c_name from student a
                LEFT JOIN score b on a.s_id = b.s_id
                LEFT JOIN course c on b.c_id=c.c_id
                where b.c_id =(select c_id from course c,teacher d where c.t_id=d.t_id and d.t_name='张三')
                and b.s_score in (select MAX(s_score) from score where c_id='02')
    
    
    -- 41、查询不同课程成绩相同的学生的学生编号、课程编号、学生成绩 
        select DISTINCT b.s_id,b.c_id,b.s_score from score a,score b where a.c_id != b.c_id and a.s_score = b.s_score
    
    
    -- 42、查询每门功成绩最好的前两名 
            -- 牛逼的写法
        select a.s_id,a.c_id,a.s_score from score a
            where (select COUNT(1) from score b where b.c_id=a.c_id and b.s_score>=a.s_score)<=2 ORDER BY a.c_id
    
    
    -- 43、统计每门课程的学生选修人数(超过5人的课程才统计)。要求输出课程号和选修人数,查询结果按人数降序排列,若人数相同,按课程号升序排列  
            select c_id,count(*) as total from score GROUP BY c_id HAVING total>5 ORDER BY total,c_id ASC
    
    -- 44、检索至少选修两门课程的学生学号 
            select s_id,count(*) as sel from score GROUP BY s_id HAVING sel>=2
    
    -- 45、查询选修了全部课程的学生信息 
            select * from student where s_id in(        
                select s_id from score GROUP BY s_id HAVING count(*)=(select count(*) from course))
    
    
    --46、查询各学生的年龄
        -- 按照出生日期来算,当前月日 < 出生年月的月日则,年龄减一
    
        select s_birth,(DATE_FORMAT(NOW(),'%Y')-DATE_FORMAT(s_birth,'%Y') - 
                    (case when DATE_FORMAT(NOW(),'%m%d')>DATE_FORMAT(s_birth,'%m%d') then 0 else 1 end)) as age
            from student;
    
    
    -- 47、查询本周过生日的学生
        select * from student where WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))=WEEK(s_birth)
        select * from student where YEARWEEK(s_birth)=YEARWEEK(DATE_FORMAT(NOW(),'%Y%m%d'))
    
        select WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))
    
    -- 48、查询下周过生日的学生
        select * from student where WEEK(DATE_FORMAT(NOW(),'%Y%m%d'))+1 =WEEK(s_birth)
    
    -- 49、查询本月过生日的学生
    
        select * from student where MONTH(DATE_FORMAT(NOW(),'%Y%m%d')) =MONTH(s_birth)
    
    -- 50、查询下月过生日的学生
        select * from student where MONTH(DATE_FORMAT(NOW(),'%Y%m%d'))+1 =MONTH(s_birth)
    展开全文
  • 练习题sql语句 -- 1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数 select a.* ,b.s_score as 01_score,c.s_score as 02_score from student a ' ' or c.c_id = NULL where b.s_score>c.s_score -- 2、...
  • 练习题sql语句 -- 1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数 select a.* ,b.s_score as 01_score,c.s_score as 02_score from student a join score b on a.s_id=b.s_id and b.c_id='01' left join...
  • 原文为MySQL语句练习,需要的点击这里 表名与字段 –1.学生表 Student(s_id,s_name,s_birth,s_sex) --学生编号,学生姓名, 出生年月,学生性别 –2.课程表 Course(c_id,c_name,t_id) – --课程编号, 课程名称, 教师...
  • 练习题sql语句 -- 1、查询"01"课程比"02"课程成绩高的学生的信息及课程分数 select a.* ,b.s_score as 01_score,c.s_score as 02_score from student a join score b on a.s_id=b.s_id and b.c_id='01' left...

空空如也

空空如也

1 2 3 4 5 ... 20
收藏数 391
精华内容 156
关键字:

sql语句练习50题