Mysql 常用语句实战2

前置 sql 语句

用来创建表、插入数据

SET NAMES utf8mb4;
SET FOREIGN_KEY_CHECKS = 0;

-- ----------------------------
-- Table structure for course ----------------------------
DROP TABLE IF EXISTS `course`;
CREATE TABLE `course`  (
  `Cno` int(11) NOT NULL COMMENT '课程编号',`Cname` varchar(255) CHaraCTER SET utf8 COLLATE utf8_general_ci NULL DEFAULT 课程名称11) 老师编号PRIMARY KEY (`Cno`) USING BTREE
) ENGINE = InnoDB SET = utf8 COLLATE = utf8_general_ci ROW_FORMAT = Compact;

 Records of courseINSERT INTO `course` VALUES (1,数学',1);
2,1)">语文23,1)">英文);

 Table structure for sc `sc`;
 `sc`  (
  `Sno` 学号score` 分数 (`Sno`,`Cno`) USING BTREE
) ENGINE  Records of scINTO `sc` 99805070904,1); font-weight: bold">6040 Table structure for student `student`;
 `student`  (
  `Sno` 255) 姓名年龄性别 (`Sno`) USING BTREE
) ENGINE  Records of studentINTO `student` 张三丰108,1)">男李小龙20,1)">小龙女17,1)">女白发魔女18,1); font-weight: bold">5,1)">韦小宝19,1)"> Table structure for teacher `teacher`;
 `teacher`  (
  `Tno` 老师名称 (`Tno`) USING BTREE
) ENGINE  Records of teacherINTO `teacher` 无崖子孤独求败洪七公1;

 

题目列表

1、查询年龄小于18岁的学员信息 

2、查询无崖子授课信息

3、查询没有参与任意课程的学生信息

4、查询无崖子每个授课课程的学员人数 统计 + 分组 

5、查询张三丰数学成绩

6、查询出语文最高分【待完成】

7、查询没有参与语文考试的学生信息

8、查询语数外三门成绩的平均分

9、查询报名孤独求败老师课程的学生信息

10、没有报名孤独求败老师课程的学生信息

 

答案列表

#1 查询年龄小于18岁的学员信息
select * from student where Sage<18;

# 查询无崖子授课信息
from teacher t join course c on c.Tno = t.Tno where t.Tname"无崖子";

#3 查询没有参与任意课程的学生信息
from student s left join sc  on s.Sno = sc.Sno where sc.score is null4 查询无崖子每个授课课程的学员人数 统计 + 分组 
select t.Tname,c.Cname,1)">count(1)  as "学员人数" on t.Tno = c.Tno join sc on sc.Cno = c.Cno group by sc.Cno HAVING t.Tname5 查询张三丰数学成绩
select s.Sname,sc.score from  student s = sc.Sno on c.Cno = sc.Cno where s.Sname="张三丰" and c.Cname"数学";

#6 查询出语文最高分【待完成】
max(sc.score) as "分数" from sc = c.Cno join student s where c.Cname"语文";

#7 查询没有参与语文考试的学生信息
on sc.Sno = s.Sno right = sc.Cno and c.Cname = "语文" and sc.score ;
from course  c ="语文" 8 查询语数外三门成绩的平均分 
select c.Cname,1)">avg(sc.score) from course c GROUP BY c.Cno;


#9 查询报名孤独求败老师课程的学生信息
join  course c on c.Cnojoin teacher t = c.Tno "孤独求败" ;
= t.Tno and t.Tname = "孤独求败" is not null;

#10 没有报名孤独求败老师课程的学生信息
null;