1、查詢"01"課程比"02"課程成績高的學生的信息及課程分數(shù)
select s.s_id, s.s_name, s.s_birth, s.s_sex, c.s_id, c.c_id, c.s_score 01score ,c1.s_score 02score from Student s inner join Score c on s.s_id = c.s_id and c.c_id = '01' left join score c1 on s.s_id = c1.s_id and c1.c_id = '02' where c.s_score > c1.s_score;
或者
select s1.*, s2.01_score, s2.02_score from student s1,(select t1.s_id as s_id, t1.s_score as 01_score,t2.s_score as 02_score from score t1,score t2 where t1.s_id = t2.s_idand t1.c_id = '01' and t2.c_id = '02' and t1.s_score > t2.s_score ) s2 where s1.s_id = s2.s_id;
2、查詢"01"課程比"02"課程成績低的學生的信息及課程分數(shù)
select s.s_id, s.s_name, s.s_birth, s.s_sex, c.s_id, c.c_id, c.s_score 01score ,c1.s_score 02score from Student s inner join Score c on s.s_id = c.s_id and c.c_id = '01' left join score c1 on s.s_id = c1.s_id and c1.c_id = '02' where c.s_score < c1.s_score;
3、查詢平均成績大于等于60分的同學的學生編號和學生姓名和平均成績
select s.s_name, s.s_id, avg(c.s_score) cvg from student s inner join score c on s.s_id = c.s_id group by s.s_id having cvg > 60;
4、查詢平均成績小于60分的同學的學生編號和學生姓名和平均成績 (包括有成績的和無成績的)
select s.s_name, s.s_id, avg(c.s_score) cvg from student s inner join score c on s.s_id = c.s_id group by s.s_id having cvg < 60 union select s.s_name, s.s_id, avg(c.s_score) cvg from student s left join score c on s.s_id = c.s_id group by s.s_id having cvg is null;
5、查詢所有同學的學生編號、學生姓名、選課總數(shù)、所有課程的總成績
select s.s_id,s.s_name name, sum(c.s_score) sum, count(1) count from student s left join score c on s.s_id = c.s_id group by s.s_id;
6、查詢"李"姓老師的數(shù)量?
select substring(t_name,1,1) as name , count(1) as count from teacher where t_name like '李%' group by name;
7、查詢學過"張三"老師授課的同學的信息?
select t.t_name tname, st.s_name stname, sc.s_score scscore from teacher t left join ?Course cou on t.t_id = cou.t_id left join score sc on cou.c_id = sc.c_id left join student st on sc.s_id = st.s_id where t.t_name = '張三';
8、 查詢沒學過"張三"老師授課的同學的信息 (吳蘭，王菊)
1.哪些學生學習 ‘張三’老師的課程 (s_id)
select st.s_id sid from teacher t left join Course cou on t.t_id = cou.t_id left join score sc on cou.c_id = sc.c_id left join student st on sc.s_id = st.s_id where t.t_name = '張三';
2.通過查詢學生表，通過where使用not int 進行過濾 ?
select * from student where student.s_id not in (select st.s_id sid from teacher t left join Course cou on t.t_id = cou.t_id left join score sc on cou.c_id = sc.c_id left join student st on sc.s_id = st.s_id where t.t_name = '張三');
9、 查詢學過編號為"01"并且也學過編號為"02"的課程的同學的信息?
1.查詢出課程編號為02的學生 sid
select * from student st inner join score sc on st.s_id = sc.s_id and sc.c_id = 02;
2.查詢出課程編碼為01的學生， 通過where sid in () 進行過濾 ?
select * from student st1 inner join score sc1 on st1.s_id = sc1.s_id and sc1.c_id = 01 where st1.s_id in (select sc.s_id from student st inner join score sc on st.s_id = sc.s_id and sc.c_id = 02)?
10、查詢學過編號為"01"但是沒有學過編號為"02"的課程的同學的信息
select * from student st1 left join score sc1 on st1.s_id = sc1.s_id and sc1.c_id = 01 where st1.s_id not in (select sc.s_id from student st left join score sc on st.s_id = sc.s_id and sc.c_id = 02);
11、 查詢沒有學全所有課程的同學的信息
1.三張分數(shù)表連接，查詢學習過所有課程的學生
select st2.s_id from student st2 inner join score sc2 on st2.s_id = sc2.s_id and sc2.c_id = 03 where st2.s_id in (select sc1.s_id from student st1 inner join score sc1 on st1.s_id = sc1.s_id and sc1.c_id = 01 where st1.s_id in (select sc.s_id from student st inner join score sc on st.s_id = sc.s_id and sc.c_id = 02))
2.通過not in 進行過濾 ?
select * from student where student.s_id not in (select st2.s_id from student st2 inner join score sc2 on st2.s_id = sc2.s_id and sc2.c_id = 03 where st2.s_id in (select sc1.s_id from student st1 inner join score sc1 on st1.s_id = sc1.s_id and sc1.c_id = 01 where st1.s_id in (select sc.s_id from student st inner join score sc on st.s_id = sc.s_id and sc.c_id = 02)));?
12 、查詢至少有一門課與學號為"01"的同學所學相同的同學的信息
1.查詢出01同學的課程信息 (c_id) ?
select sc.c_id from score sc inner join student st on sc.s_id = st.s_id where st.s_id = '01'
2.查詢所有學生c_id2 ?
select distinct st1.s_name from student st1 left join score sc1 on st1.s_id = sc1.s_id?
3.c_id2 in (c_id) , 有同學報名多門課程，可以使用distinct過濾
select distinct st1.s_name from student st1 left join score sc1 on st1.s_id = sc1.s_id where sc1.c_id in (select sc.c_id from score sc inner join student st on sc.s_id = st.s_id where st.s_id = '01');
13、查詢和"01"號的同學學習的課程完全相同的其他同學的信息?
1. 01學生學習的課程id (c_id)，我們把c_id給拼接(concat)到一起 ?
select group_concat(sc.c_id) from student st inner join score sc on st.s_id = sc.s_id and st.s_id = '01';?
查詢其他學生的信息， 也使用concat拼接到一起，或者使用 in ??
select st.s_name,group_concat(sc.c_id) cc from student st inner join score sc on st.s_id = sc.s_id group by st.s_id having cc in (select group_concat(sc.c_id) from student st inner join score sc on st.s_id = sc.s_id and st.s_id = '01');
14、查詢沒學過"張三"老師講授的任一門課程的學生姓名
1.查詢出張三講授的課程，通過課程查詢到學生的s_id ?
select sc.s_id from score sc inner join Course cu on sc.c_id = cu.c_id inner join teacher tc on cu.t_id = tc.t_id where tc.t_name = '張三';
2.not in 進行過濾 ?
select * from student where student.s_id not in (select sc.s_id from score sc inner join Course cu on sc.c_id = cu.c_id inner join teacher tc on cu.t_id = tc.t_id where tc.t_name = '張三');
15、查詢兩門及其以上不及格課程的同學的學號，姓名 及 其平均成績?
?1.where 分數(shù) < 60 , 通過 group by(s_id) 進行分組， 通過count函數(shù)進行過濾
// 60分一下的不加入統(tǒng)計?
select st.s_name, st.s_id, avg(sc.s_score) avg where sc1.s_id = st.s_id as avg from student st left join score sc on st.s_id = sc.s_id where sc.s_score < 60 group by st.s_id having count(1) >= 2?
// 60分以上的也加入統(tǒng)計 ?
select st.s_name, st.s_id, (select avg(sc1.s_score) from student st1 left join score sc1 on st1.s_id = sc1.s_id) avg where sc1.s_id = st.s_id as avg from student st left join score sc on st.s_id = sc.s_id where sc.s_score < 60 group by st.s_id having count(1) >= 2?
?2, 某個同學的平均分 ?
select avg(sc1.s_score) from student st1 left join score sc1 on st1.s_id = sc1.s_id where sc1.s_id = '01';?
16 、檢索"01"課程分數(shù)小于60，按分數(shù)降序排列的學生信息
select st.s_name, sc.c_id, sc.s_score from student st inner join score sc on st.s_id = sc.s_id and sc.c_id = '01' and sc.s_score < 60 order by sc.s_score desc;
--表信息
--學生表
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`)
);
--課程表
CREATE TABLE `Course`(
`c_id`? VARCHAR(20),
`c_name` VARCHAR(20) NOT NULL DEFAULT '',
`t_id` VARCHAR(20) NOT NULL,
PRIMARY KEY(`c_id`)
);
--教師表
CREATE TABLE `Teacher`(
`t_id` VARCHAR(20),
`t_name` VARCHAR(20) NOT NULL DEFAULT '',
PRIMARY KEY(`t_id`)
);
--成績表
CREATE TABLE `Score`(
`s_id` VARCHAR(20),
`c_id`? VARCHAR(20),
`s_score` INT(3),
PRIMARY KEY(`s_id`,`c_id`)
);
--插入學生表測試數(shù)據(jù)
insert into Student values('01' , '趙雷' , '1990-01-01' , '男');
insert into Student values('02' , '錢電' , '1990-12-21' , '男');
insert into Student values('03' , '孫風' , '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' , '吳蘭' , '1992-03-01' , '女');
insert into Student values('07' , '鄭竹' , '1989-07-01' , '女');
insert into Student values('08' , '王菊' , '1990-01-20' , '女');
--課程表測試數(shù)據(jù)
insert into Course values('01' , '語文' , '02');
insert into Course values('02' , '數(shù)學' , '01');
insert into Course values('03' , '英語' , '03');
--教師表測試數(shù)據(jù)
insert into Teacher values('01' , '張三');
insert into Teacher values('02' , '李四');
insert into Teacher values('03' , '王五');
--成績表測試數(shù)據(jù)
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);
持續(xù)更新中...
