SQL（mysql）语句查询--navicat 工具---（2）

-- 13、查询最低分大于70，最高分小于90的Sno列。
SELECT sno FROM scores GROUP BY sno HAVING MAX(degree) < 90 and MIN(degree) >70
-- 14、查询所有学生的Sname、Cno和Degree列。
SELECT a.sno,a.sname,b.degree from students as a INNER JOIN scores as b on a.sno = b.sno
SELECT a.sname,b.cno,b.degree from students as a INNER JOIN scores as b on a.sno = b.sno ORDER BY a.sname
-- 15、查询所有学生的Sno、Cname和Degree列。
SELECT a.sno,b.cname,a.degree FROM scores as a INNER JOIN courses as b  on a.cno = b.cno ORDER BY a.sno
-- 16、查询所有学生的Sname、Cname和Degree列。
SELECT
    a.sname,
    c.cname,
    b.degree
FROM
    students AS a
INNER JOIN scores AS b ON (a.sno = b.sno)
INNER JOIN courses AS c ON (b.cno = c.cno)
-- GROUP BY c.cname
ORDER BY
    a.sname 
-- 17、查询“95033”班所选课程的平均分。
SELECT
    c.cname,
    AVG(degree)
FROM
    students AS a
INNER JOIN scores AS b ON (a.sno = b.sno)
INNER JOIN courses AS c ON (b.cno = c.cno)
WHERE
    a.class = '95033'
GROUP BY
    c.cname
ORDER BY
    a.sname 

SELECT
    c.cname,
    AVG(degree)
FROM
    students AS a
INNER JOIN scores AS b ON (a.sno = b.sno)
INNER JOIN courses AS c ON (b.cno = c.cno)
WHERE
    a.class = '95033'
ORDER BY
    a.sname 

-- 18、假设使用如下命令建立了一个grade表：
 create table grade(low   number(3,0),upp   number(3),rank   char(1));
 insert into grade values(90,100,’A’);
insert into grade values(80,89,’B’);
insert into grade values(70,79,’C’);
insert into grade values(60,69,’D’);
insert into grade values(0,59,’E’);
commit;
-- 现查询所有同学的Sno、Cno和rank列。
-- 19、查询选修“3-105”课程的成绩高于“109”号同学成绩的所有同学的记录。
SELECT a.sno,a.cno,a.degree from scores as a INNER JOIN scores as b on (a.cno = b.cno and a.degree > b.degree)
where a.cno = '3-105' AND b.sno = '109'

-- 20、查询score中选学一门以上课程的同学中分数为非最高分成绩的记录。
SELECT * from scores GROUP BY sno HAVING COUNT(cno) > 1 and degree != MAX(degree)

-- 21、查询成绩高于学号为“109”、课程号为“3-105”的成绩的所有记录。
SELECT * FROM scores as a INNER JOIN scores as b on (a.sno = b.sno and a.degree > b.degree) where b.sno = '109' and  a.cno = '3-105'
-- 22、查询和学号为108的同学同年出生的所有学生的Sno、Sname和Sbirthday列。
SELECT a.sno,a.sname,a.sbirthday FROM students as a INNER JOIN students as b on (YEAR(a.sbirthday) = (YEAR(a.sbirthday)))
WHERE b.sno = '108'

-- 23、查询“张旭“教师任课的学生成绩。
SELECT a.sno,a.degree
FROM scores as a INNER JOIN courses as b on (a.cno = b.cno) INNER JOIN teachers as c 
ON (b.tno = c.tno) WHERE c.tname = '张旭' 

-- 24、查询选修某课程的同学人数多于5人的教师姓名。

SELECT DISTINCT tname FROM scores as a INNER JOIN courses as b on (a.cno = b.cno)
INNER JOIN teachers as c ON (b.tno = c.tno) where b.cno in 
(SELECT cno from scores GROUP BY cno HAVING COUNT(sno) > 5)