一、修改数据库表和表中的字段的编码格式.
修改表的编码格式:
ALTER TABLE `table` DEFAULT CHARACTER SET utf8;
修改字段的编码格式:
ALTER TABLE `tablename` CHANGE `字段名1` `字段名2` VARCHAR(36) CHARACTER SET utf8 NOT NULL;
修改一张表中所有字段的编码格式:
alter table `tablename` convert to character set utf8;
二、查询位于某一个范围内的数,可以用BETWEEN
三、SQL练习
建表如下:
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)
插入数据:
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Student表中的所有记录的sname、ssex和class列
SELECT sname,ssex,class FROM student;
2.查询教师所有的单位即不重复的depart列。
SELECT DISTINCT depart FROM teachers;
3.查询students表的所有记录
SELECT * FROM students;
4.查询Score表中成绩在60到80之间的所有记录。
SELECT * FROM scores WHERE degree BETWEEN 60 AND 80;
5.查询Score表中成绩为85,86或88的记录。
SELECT * FROM scores WHERE segree IN (85,86,88);
6.查询student表中“95031”班或性别为“女”的同学记录。
SELECT * FROM students WHRER class='95031' or ssex='女';
7.以Class降序查询Student表的所有记录。
SELECT * FROM `students` ORDER BY class DESC
8.以Cno升序、Degree降序查询Score表的所有记录。
SELECT * FROM Scores ORDER BY Cno,Degree DESC;
9.查询“95031”班的学生人数。
SELECT COUNT(1) AS StuNum FROM Students WHERE Class='95031';
10.查询Score表中的最高分的学生学号和课程号。
SELECT sno,cno FROM scores WHERE degree in (SELECT max(degree) FROM scores);
11.查询‘3-105’号课程的平均分。
SELECT AVG (degree) AS aveScore FROM scores WHERE cno = '3-105'
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。(HAVING)
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。(HAVING)
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。(INNER JOIN)
SELECT
sname,
cno,
degree
FROM
`students`
INNER JOIN
scores ON(students.sno = scores.sno)
ORDER BY
sname
15.查询所有学生的Sno、Cname和Degree列。
SELECT
sno,
cname,
degree
FROM
`scores`
INNER JOIN
courses ON scores.cno = courses,
cno
ORDER BY
sno;
16.查询所有学生的Sname、Cname和Degree列。
SELECT
sname,
cname,
degree
FROM
`students`
INNER JOIN
scores ON students.sno = scores.sno
INNER JOIN
courses ON scores.cno = courses.cno
ORDER BY
sname
17.查询“95033”班所选课程的平均分。
SELECT
cname,
AVG(degree)
FROM
`students`
INNER JOIN
scores ON students.sno = scores.sno
INNER JOIN
courses ON scores.cno = courses.cno
WHERE
class = '95033'
GROUP BY
courses.cno
ORDER BY
cname
18.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
*
FROM
students,
scores
WHERE
scores.Cno = '3-105' AND students.sno = scores.sno AND scores.degree >(
SELECT
degree
FROM
scores
WHERE
cno = '3-105' AND sno = '109'
)
19.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。
这里写代码片
20.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,
students
WHERE
scores.sno = students.sno AND degree >(
SELECT
degree
FROM
scores
WHERE
sno = '109' AND cno = '3-105'
)
21.查询和学号为107的同学同年出生的所有学生的Sno、Sname和Sbirthday列。
SELECT
sno,
sname,
sbirthday
FROM
students
WHERE YEAR
(students.sbirthday) =(
SELECT YEAR
(sbirthday)
FROM
students
WHERE
sno = '107'
)
22.查询“张旭“教师任课的学生成绩。
SELECT
sno,
cno,
degree
FROM
scores
WHERE
cno IN(
SELECT
cno
FROM
courses
WHERE
tno IN(
SELECT
tno
FROM
teachers
WHERE
tname = '张旭'
)
)
23.查询选修某课程的同学人数多于5人的教师姓名。
SELECT
tname
FROM
teachers
WHERE
tno IN(
SELECT
tno
FROM
courses
WHERE
cno IN(
SELECT
cno
FROM
scores
GROUP BY
cno
HAVING COUNT
(*) > 5
)
)
24.查询95033班和95031班全体学生的记录。
SELECT
*
FROM
students
WHERE
class IN('95033',
'95011')
ORDER BY
class
25.查询存在有85分以上成绩的课程Cno。
SELECT DISTINCT
cno
FROM
scores
WHERE
degree > 80
26.查询出“计算机系“教师所教课程的成绩表。
SELECT
*
FROM
`scores`
WHERE
cno IN(
SELECT
cno
FROM
courses
WHERE
tno IN(
SELECT
tno
FROM
teachers
WHERE
depart = '计算机系'
)
)
27.查询“计算机系”与“电子工程系“不同职称的教师的Tname和Prof。
这里写代码片