mysql日常基本語句

注：基於（https://blog.csdn.net/xiaosa_kun/article/details/84868547）所修改，修改查詢語句的第16，27。

1.新建數據庫

CREATE DATABASE school;

設有一個數據庫school，包括四個表：學生表（student）、課程表（course）、成績表（score）以及教師信息表（teacher）。用SQL語句創建四個表並完成相關題目。
創建學生表

CREATE TABLE student (
	sno varchar(20) NOT NULL PRIMARY KEY, 
	sname varchar(20) NOT NULL, 
	ssex varchar(20) NOT NULL, 
	sbirthday datetime, 
	class varchar(20)
) ENGINE = innodb CHARSET = utf8;

創建教師表

CREATE TABLE teacher (
	tno varchar(20) NOT NULL PRIMARY KEY, 
	tname varchar(20) NOT NULL, 
	tsex varchar(20) NOT NULL, 
	tbirthday datetime, 
	prof varchar(20), 
	depart varchar(20) NOT NULL
) ENGINE = innodb CHARSET = utf8;

創建課程表

CREATE TABLE course (
	cno varchar(20) NOT NULL PRIMARY KEY, 
	cname varchar(20) NOT NULL, 
	tno varchar(20) NOT NULL, 
	FOREIGN KEY (tno) REFERENCES teacher (tno)
) ENGINE = innodb CHARSET = utf8;

創建成績表

CREATE TABLE score (
	sno varchar(20) NOT NULL, 
	FOREIGN KEY (sno) REFERENCES student (sno), 
	cno varchar(20) NOT NULL, 
	FOREIGN KEY (cno) REFERENCES course (cno), 
	degree decimal NOT NULL
) ENGINE = innodb CHARSET = utf8;

2.插入數據庫

插入學生表數據

use student;
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (108 ,'曾華' ,'男' ,'1977-09-01',95033);
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (105 ,'匡明' ,'男' ,'1975-10-02',95031);
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (107 ,'王麗' ,'女' ,'1976-01-23',95033);
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (101 ,'李軍' ,'男' ,'1976-02-20',95033);
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (109 ,'王芳' ,'女' ,'1975-02-10',95031);
INSERT INTO STUDENT (SNO,SNAME,SSEX,SBIRTHDAY,CLASS) VALUES (103 ,'陸君' ,'男' ,'1974-06-03',95031);

插入教師表數據

use teacher;
INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (804,'李誠','男','1958-12-02','副教授','計算機系');
INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (856,'張旭','男','1969-03-12','講師','電子工程系');
INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (825,'王萍','女','1972-05-05','助教','計算機系');
INSERT INTO TEACHER(TNO,TNAME,TSEX,TBIRTHDAY,PROF,DEPART) VALUES (831,'劉冰','女','1977-08-14','助教','電子工程系');

插入課程表數據

use course;
INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('3-105' ,'計算機導論',825);
INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('3-245' ,'操作系統' ,804);
INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('6-166' ,'數據電路' ,856);
INSERT INTO COURSE(CNO,CNAME,TNO)VALUES ('9-888' ,'高等數學' ,831);

插入成績表數據

use score;
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (103,'3-245',86);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (105,'3-245',75);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (109,'3-245',68);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (103,'3-105',92);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (105,'3-105',88);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (109,'3-105',76);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (101,'3-105',64);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (107,'3-105',91);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (108,'3-105',78);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (101,'6-166',85);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (107,'9-888',79);
INSERT INTO SCORE(SNO,CNO,DEGREE)VALUES (108,'6-166',81);

3.查詢數據

1、 查詢Student表中的所有記錄的Sname、Ssex和Class列。

SELECT sname, ssex, class
FROM student;

2、 查詢教師所有的單位即不重複的Depart列。

SELECT depart
FROM teacher
GROUP BY depart;

3、 查詢Student表的所有記錄。

SELECT *
FROM student;

4、 查詢Score表中成績在60到80之間的所有記錄。(between)

SELECT *
FROM score
WHERE degree BETWEEN 60 AND 80;

5、 查詢Score表中成績爲85，86或88的記錄。(in)

SELECT *
FROM score
WHERE degree IN (85, 86, 88);

6、 查詢Student表中“95031”班或性別爲“女”的同學記錄。

SELECT *
FROM student
WHERE class = '95031'
	OR ssex = '女';

7、 以Class降序查詢Student表的所有記錄。

SELECT *
FROM student
ORDER BY class DESC;

8、 以Cno升序、Degree降序查詢Score表的所有記錄

SELECT *
FROM score
ORDER BY cno ASC, degree DESC;

9、 查詢“95031”班的學生人數。

SELECT COUNT(*)
FROM student
WHERE class = '95031';

10、查詢Score表中的最高分的學生學號和課程號。(排序)

SELECT sno, cno
FROM score
ORDER BY degree DESC;

11、查詢每門課的平均成績。(group by)

SELECT cname, AVG(degree)
FROM score
	INNER JOIN course
WHERE course.cno = score.cno
GROUP BY course.cname;

12、查詢Score表中至少有5名學生選修的並以3開頭的課程的平均分數。(group by having)

SELECT cno, AVG(degree)
FROM score
WHERE cno LIKE '3%'
GROUP BY cno
HAVING COUNT(sno) >= 5;

13、查詢最低分大於70，最高分小於90的Sno列。

SELECT sno
FROM score
GROUP BY sno
HAVING MAX(degree) < 90
AND MIN(degree) > 70;

14、查詢所有學生的Sname、Cno和Degree列。

SELECT sname, score.cno, degree
FROM student
	INNER JOIN score
WHERE student.sno = score.sno;

15、查詢所有學生的Sno、Cname和Degree列。

SELECT student.sno, sname, degree
FROM student
	INNER JOIN score
WHERE student.sno = score.sno;

16、查詢所有學生的Sname、Cname和Degree列。

select sname,cname,degree
from student 
inner join score,course
where
course.cno = score.cno and student.sno = score.sno;

17、查詢“95033”班學生的平均分。(選)

SELECT AVG(degree)
FROM student
	INNER JOIN score
WHERE class = '95033'
	AND student.sno = score.sno;

18、假設使用如下命令建立了一個grade表,並查詢所有同學的Sno、Cno和rank列。

create table grade(low int(3),high int(3),rank varchar(20));
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;

select sno,cno,rank 
from score 
inner join grade 
where degree < high and degree >low;

19、查詢成績高於學號爲“109”、課程號爲“3-105”的成績的所有記錄。(選)

SELECT *
FROM score
WHERE degree > (
	SELECT degree
	FROM score
	WHERE sno = '109'
		AND cno = '3-105'
	);

20、查詢和學號爲108的同學同年出生的所有學生的Sno、Sname和Sbirthday列。(選)

SELECT sno, sname, sbirthday
FROM student, (SELECT year(sbirthday) AS birthyear
		FROM student
		WHERE sno = 108
		) s1
WHERE year(sbirthday) = s1.birthyear;

21、查詢“張旭“教師任課的學生成績。(選)

SELECT tname, cname, sname, degree
FROM teacher, course, student, score
WHERE teacher.tno = course.tno
	AND course.cno = score.cno
	AND score.sno = student.sno
	AND teacher.tname = '張旭';

22、查詢95033班和95031班全體學生的記錄。(in)

SELECT *
FROM student
WHERE class IN ('95033', '95031');

23、查詢存在有85分以上成績的課程cno.

SELECT cno
FROM score
GROUP BY cno
HAVING MAX(degree) >= 85;

24、查詢出“計算機系“教師所教課程的成績表。(選)

SELECT score.sno, sname, degree
FROM teacher, score, course, student
WHERE teacher.tno = course.tno
	AND course.cno = score.cno
	AND score.sno = student.sno
	AND teacher.depart = '計算機系';

25、查詢成績比該課程平均成績低的同學的成績表。(選)

SELECT s.sno, s.cno, s.degree
FROM score AS s, (SELECT cno, AVG(degree) AS avgd
		FROM score
		GROUP BY cno
		) avgs
WHERE s.cno = avgs.cno
	AND s.degree < avgs.avgd;

26、查詢所有任課教師的Tname和Depart.(選)

SELECT tname, depart
FROM teacher;

27、查詢至少有2名男生的班號。(group by having)

SELECT class, COUNT(sname)
FROM student
GROUP BY class
HAVING COUNT(sname) >= 2;

28、查詢Student表中不姓“王”的同學記錄。(not like)

SELECT *
FROM student
WHERE sname NOT LIKE '王%';

29、查詢Student表中每個學生的姓名和年齡。

SELECT sname, 2018 - year(sbirthday) AS age
FROM student;

30、查詢Student表中最大和最小的Sbirthday日期值。

SELECT MAX(sbirthday), MIN(sbirthday)
FROM student;

31、以班號和年齡從大到小的順序查詢Student表中的全部記錄。
下面兩種SQL語句一樣的效果，年齡大則出生日期小

SELECT *
FROM student
ORDER BY class DESC, sbirthday ASC;

SELECT *
FROM student
ORDER BY class DESC, sbirthday;

32、查詢“男”教師及其所上的課程。

SELECT tname, cname
FROM teacher, course
WHERE teacher.tno = course.tno
	AND tsex = '男';

33、查詢每一門科目最高分同學的Sno、Cno和Degree列。(選)

SELECT sno, cno, MAX(degree)
FROM score
GROUP BY cno;