sql题
常见的学生老师课程分数：
建表：
CREATE TABLE students
(sno VARCHAR(3) NOT NULL,
sname VARCHAR(4) NOT NULL,
ssex VARCHAR(2) NOT NULL,
sbirthday DATETIME,
class VARCHAR(5))
CREATE TABLE courses
(cno VARCHAR(5) NOT NULL,
cname VARCHAR(10) NOT NULL,
tno VARCHAR(10) NOT NULL)
CREATE TABLE scores
(sno VARCHAR(3) NOT NULL,
cno VARCHAR(5) NOT NULL,
degree NUMERIC(10, 1) NOT NULL)
CREATE TABLE teachers
(tno VARCHAR(3) NOT NULL,
tname VARCHAR(4) NOT NULL, tsex VARCHAR(2) NOT NULL,
tbirthday DATETIME NOT NULL, prof VARCHAR(6),
depart VARCHAR(10) NOT NULL)
插数：
INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (108 ,'曾华' ,'男' ,'1977-09-01',95033);
INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (105 ,'匡明' ,'男' ,'1975-10-02',95031);
INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (107 ,'王丽' ,'女' ,'1976-01-23',95033);
INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (101 ,'李军' ,'男' ,'1976-02-20',95033);
INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (109 ,'王芳' ,'女' ,'1975-02-10',95031);
INSERT INTO STUDENTS (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (103 ,'陆君' ,'男' ,'1974-06-03',95031);
INSERT INTO COURSES(CNO,CNAME,TNO)VALUES ('3-105' ,'计算机导论',825);
INSERT INTO COURSES(CNO,CNAME,TNO)VALUES ('3-245' ,'操作系统' ,804);
INSERT INTO COURSES(CNO,CNAME,TNO)VALUES ('6-166' ,'数据电路' ,856);
INSERT INTO COURSES(CNO,CNAME,TNO)VALUES ('9-888' ,'高等数学' ,100);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (103,'3-245',86);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (105,'3-245',75);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (109,'3-245',68);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (103,'3-105',92);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (105,'3-105',88);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (109,'3-105',76);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (101,'3-105',64);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (107,'3-105',91);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (108,'3-105',78);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (101,'6-166',85);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (107,'6-106',79);
INSERT INTO SCORES(SNO,CNO,DEGREE)VALUES (108,'6-166',81);
INSERT INTO TEACHERS(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (804,'李诚','男','1958-12-02','副教授','计算机系');
INSERT INTO TEACHERS(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (856,'张旭','男','1969-03-12','讲师','电子工程系');
INSERT INTO TEACHERS(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (825,'王萍','女','1972-05-05','助教','计算机系');
INSERT INTO TEACHERS(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (831,'刘冰','女','1977-08-14','助教','电子工程系');
---------------------
12.查询Score表中至少有5名学生选修的并以3开头的课程的平均分数。
SELECT Cno,AVG(Degree)
FROM Scores
WHERE Cno LIKE '3%'
GROUP BY Cno
HAVING COUNT(Sno) >= 5;
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;
18.假设使用如下命令建立了一个grade表：
CREATE TABLE grade(low TINYINT,upp TINYINT,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');
现查询所有同学的Sno、Cno和rank列。
解法1：
SELECT SNO,CNO,RANK FROM scores,GRADE WHERE DEGREE BETWEEN LOW AND UPP
ORDER BY Sno;
解法2：
SELECT Sno,Cno,rank
FROM Scores INNER JOIN grade
ON(Scores.Degree>=grade.low AND Scores.Degree<=grade.upp)
ORDER BY Sno;
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 s1.Sno,s1.Degree
FROM Scores AS s1 INNER JOIN Scores AS s2
ON(s1.Cno=s2.Cno AND s1.Degree>s2.Degree)
WHERE s1.Cno='3-105' AND s2.Sno='109'
ORDER BY s1.Sno;
另外两种解法：
1.
SELECT A.* FROM SCOREs A JOIN SCOREs B WHERE A.CNO='3-105' AND A.DEGREE>B.DEGREE AND
B.SNO='109' AND B.CNO='3-105';
2.
SELECT A.* FROM SCOREs A WHERE A.CNO='3-105' AND A.DEGREE>ALL(SELECT DEGREE FROM
SCOREs B WHERE B.SNO='109' AND B.CNO='3-105');
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 s1.Sno,s1.Degree
FROM Scores AS s1 INNER JOIN Scores AS s2
ON(s1.Cno=s2.Cno AND s1.Degree>s2.Degree)
WHERE s1.Cno='3-105' AND s2.Sno='109'
ORDER BY s1.Sno;
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。
解法1：
SELECT SNO,SNAME,SBIRTHDAY
FROM STUDENTs WHERE YEAR(SBIRTHDAY)=(SELECT YEAR(SBIRTHDAY) FROM STUDENTs WHERE SNO='108');
解法2：
SELECT s1.Sno,s1.Sname,s1.Sbirthday
FROM Students AS s1 INNER JOIN Students AS s2
ON(YEAR(s1.Sbirthday)=YEAR(s2.Sbirthday))
WHERE s2.Sno='108';
23.查询“张旭“教师任课的学生成绩。
解法1：
SELECT Sno,Degree
FROM Scores INNER JOIN Courses
ON(Scores.Cno=Courses.Cno) INNER JOIN Teachers
ON(Courses.Tno=Teachers.Tno)
WHERE Teachers.Tname='张旭';
解法2：
SELECT A.SNO,A.DEGREE
FROM scores A JOIN (TEACHERs B,COURSEs C)
ON A.CNO=C.CNO AND B.TNO=C.TNO
WHERE B.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 INNER JOIN Courses
ON(Scores.Cno=Courses.Cno) INNER JOIN Teachers
ON(Courses.Tno=Teachers.Tno)
WHERE Courses.Cno IN(SELECT Cno FROM Scores GROUP BY(Cno) HAVING COUNT(Sno)>5);
27.查询出“计算机系“教师所教课程的成绩表。
SELECT Tname,Cname,SName,Degree
FROM Teachers INNER JOIN Courses
ON(Teachers.Tno=Courses.Tno) INNER JOIN Scores
ON(Courses.Cno=Scores.Cno) INNER JOIN Students
ON(Scores.Sno=Students.Sno)
WHERE Teachers.Depart='计算机系'
ORDER BY Tname,Cname,Degree DESC;
28.查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。
SELECT Tname,Prof
FROM Teachers
WHERE Depart='计算机系' AND Prof NOT IN(
SELECT DISTINCT Prof
FROM Teachers
WHERE Depart='电子工程系');
29.查询选修编号为“3-105“课程且成绩至少高于任意选修编号为“3-245”的同学的成绩的Cno、Sno和Degree,并按Degree从高到低次序排序。
SELECT Cno,Sno,Degree
FROM Scores
WHERE Cno='3-105' AND Degree > ANY(
SELECT Degree
FROM Scores
WHERE Cno='3-245')
ORDER BY Degree DESC;
30.查询选修编号为“3-105”且成绩高于所有选修编号为“3-245”课程的同学的Cno、Sno和Degree.
SELECT Cno,Sno,Degree
FROM Scores
WHERE Cno='3-105' AND Degree > ALL(
SELECT Degree
FROM Scores
WHERE Cno='3-245')
ORDER BY Degree DESC;
32.查询所有“女”教师和“女”同学的name、sex和birthday.
SELECT Sname,Ssex,Sbirthday
FROM Students
WHERE Ssex='女'
UNION
SELECT Tname,Tsex,Tbirthday
FROM Teachers
WHERE Tsex='女';
33.查询成绩比该课程平均成绩低的同学的成绩表。
SELECT s1.*
FROM Scores AS s1 INNER JOIN (
SELECT Cno,AVG(Degree) AS aDegree
FROM Scores
GROUP BY Cno) s2
ON(s1.Cno=s2.Cno AND s1.Degree<s2.aDegree);
34.查询所有任课教师的Tname和Depart.
SELECT Tname,Depart
FROM Teachers
WHERE Tno IN(
SELECT Tno
FROM Courses
);
35.查询所有未讲课的教师的Tname和Depart.
SELECT Tname,Depart
FROM Teachers
WHERE Tno NOT IN(
SELECT Tno
FROM Courses
);
36.查询至少有2名男生的班号。
SELECT Class,COUNT(1) AS boyCount
FROM Students
WHERE Ssex='男'
GROUP BY Class
HAVING boyCount>=2;
38.查询Student表中每个学生的姓名和年龄。
SELECT Sname,YEAR(NOW())-YEAR(Sbirthday) AS Sage
FROM Students;
39.查询Student表中最大和最小的Sbirthday日期值。
SELECT MIN(Sbirthday),MAX(Sbirthday)
FROM Students;
41.查询“男”教师及其所上的课程。
SELECT Teachers.Tname,Courses.Cname
FROM Teachers INNER JOIN Courses
ON(Teachers.Tno=Courses.Tno)
WHERE Teachers.Tsex='男';
42.查询最高分同学的Sno、Cno和Degree列。
SELECT *
FROM Scores
GROUP BY Cno
HAVING Degree=Max(Degree);
44.查询和“李军”同性别并同班的同学Sname.
SELECT s1.Sname
FROM Students AS s1 INNER JOIN Students AS s2
ON(s1.Ssex=s2.Ssex AND s1.Class=s2.Class)
WHERE s2.Sname='李军';
45.查询所有选修“计算机导论”课程的“男”同学的成绩表
SELECT *
FROM Scores
WHERE Sno IN (
SELECT Sno
FROM Students
WHERE Ssex='男') AND
Cno IN (
SELECT Cno
FROM Courses
WHERE Cname='计算机导论');
递归查询：
CREATE TABLE `digui` (
`id` int(11) NOT NULL AUTO_INCREMENT,
`parent_id` int(255) DEFAULT NULL,
`name` varchar(255) DEFAULT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=6 DEFAULT CHARSET=utf8mb4;
表结构
SELECT t1.name 城市,t2.name 街区,t3.name 道路
FROM digui t1
LEFT JOIN digui t2 ON t1.id = t2.parent_id
LEFT JOIN digui t3 ON t2.id = t3.parent_id
WHERE t1.id = '1';
结果
参考链接：https://blog.csdn.net/mrbcy/article/details/68965271
