概述

续一下之前讲的MySQL数据库sql基础练习第三部分，大家可以跟着做一下。

建表语句

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)

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');

1、查询所有教师和同学的name、sex和birthday.

2、查询所有“女”教师和“女”同学的name、sex和birthday.

3、查询成绩比该课程平均成绩低的同学的成绩表。

4、查询所有任课教师的Tname和Depart.

5 查询所有未讲课的教师的Tname和Depart.

6、查询至少有2名男生的班号。

7、查询Student表中不姓“王”的同学记录。

8、查询Student表中每个学生的姓名和年龄。

9、查询Student表中最大和最小的Sbirthday日期值。

10、以班号和年龄从大到小的顺序查询Student表中的全部记录。

11、查询“男”教师及其所上的课程。

12、查询最高分同学的Sno、Cno和Degree列。

13、查询和“李军”同性别的所有同学的Sname.

14、查询和“李军”同性别并同班的同学Sname.

15、查询所有选修“计算机导论”课程的“男”同学的成绩表

答案

1.查询所有教师和同学的name、sex和birthday.

SELECT Sname,Ssex,Sbirthday FROM Students UNION SELECT Tname,Tsex,Tbirthday FROM Teachers;

2.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';

3.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); 

4.查询所有任课教师的Tname和Depart.

SELECT Tname,Depart FROM Teachers WHERE Tno IN( SELECT Tno FROM Courses);

5.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);

6.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;

7.查询Student表中不姓“王”的同学记录。

SELECT * FROM Students WHERE Sname NOT LIKE '王%';

8.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;

9.查询Student表中最大和最小的Sbirthday日期值。

SELECT MIN(Sbirthday),MAX(Sbirthday) FROM Students;

10.以班号和年龄从大到小的顺序查询Student表中的全部记录。

SELECT * FROM Students ORDER BY Class DESC,Sbirthday ASC;

11.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';

12.查询最高分同学的Sno、Cno和Degree列。

SELECT * FROM Scores GROUP BY Cno HAVING Degree=Max(Degree);

13.查询和“李军”同性别的所有同学的Sname.

SELECT s1.Sname FROM Students AS s1 INNER JOIN Students AS s2 ON(s1.Ssex=s2.Ssex) WHERE s2.Sname='李军';

14.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';

15.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');

到这里我们的sql练习部分就讲完了，建议大家有空可以自己在MySQL数据库上测试一下，三个部分做下来也就一个小时，强化下基础还是可以的，侧重去考虑如何写才能更高效。

后面小编会分享更多DBA方面内容，感兴趣的朋友走一波关注哩~