MySQL操作实践

SELECT yyy as 年 FROM employee_tb WHERE  name1 IN ('CHu','232')；

UPDATE employee_tb SET daily_typing_pages =0  WHERE  name1 IN ('CHu','232')

SELECT * FROM employee_tb WHERE id LIKE '%'

SELECT * FROM employee_tb WHERE id LIKE '%' ORDER BY yyy ASC

自连接
SELECT a.name1 FROM employee_tb a LEFT JOIN employee_tb b ON a.name1=b.name1;

AND
SELECT * FROM employee_tb WHERE daily_typing_pages= 322 AND name1 NOT IN('232');

create table log(
logid int ( 4 ) primary key not  null  auto_increment,
logtitle varchar(32 ) not  null ,
logcontent varchar(160 ) not  null ,
logtime datetime not null ,
userip varchar(64 ) not  null
);

CREATE TABLE TV1(rid int PRIMARY KEY auto_increment NOT NULL,uid INT,channel VARCHAR(10));

INSERT INTO table_name (列1, 列2,...) VALUES (值1, 值2,....)

SELECT * FROM tv WHERE channel='fujian' and uid NOT IN( SELECT a.uid from tv a LEFT JOIN tv b ON a.uid=b.uid WHERE a.channel='hunan' AND b.channel='fujian');

use geek;
set default_storage_engine=INNODB;
CREATE TABLE table_0410(today datetime,name CHAR(20));

use geek;
INSERT into table_0408 VALUES(NOW(),'a');

show TABLES;//展示表结构

show GLOBAL VARIABLES LIKE 'innodb_data_file_path'

show VARIABLES;

FLUSH TABLES WITH READ LOCK;//备份时锁住数据库
INSERT INTO table_0408 VALUES(NOW(),NULL);//此时会冲突
UNLOCK TABLES;

SHOW VARIABLES LIKE 'time_zone'

USE geek;
CREATE TABLE today(t1 datetime,
t2 TIMESTAMP);

SET time_zone='system';
show VARIABLES LIKE 'time_zone';
SELECT * FROM today;
SET time_zone='+12:00';
SHOW VARIABLES LIKE 'time_zone';
SELECT * FROM today;

UPDATE today SET t1=NOW();
SELECT * FROM today;
SELECT NOW(),CURTIME();

USE geek;
CREATE TABLE person(
sex enum('男','女'),
interest SET('听音乐','购物','旅游')
);//枚举单选，set多选
INSERT INTO persons (`sex`, `interest`) VALUES ('男', '听音乐,旅游')

set sql_mode='strict_trans_tables';
INSERT INTO persons (`sex`, `interest`) VALUES ('男', '音乐,旅游,购物')；//报错

use geek;
SET SQL_mode='ansi';
INSERT INTO persons (`sex`, `interest`) VALUES ('男', '音乐,旅游,购物');//不报错

设置主键
use geek;
CREATE TABLE nowadays(
t1 datetime,
t2 TIMESTAMP,
PRIMARY KEY(t1,t2)
)

//查看某个表的约束条件
SELECT CONSTRAINT_name,CONSTRAINT_type
FROM information_schema.TABLE_CONSTRAINTS
WHERE TABLE_SCHEMA='geek' and TABLE_NAME='nowadays';

//查看表结构
show INDEX FROM nowadays

CREATE TABLE Table_0411(
sno CHAR(10),
sname CHAR(10),
CONSTRAINT s_pk PRIMARY KEY(sno),
CONSTRAINT s_uq UNIQUE (sname)
)

CREATE DATABASE choose;
USE choose;

CREATE TABLE teacher(
teacher_no CHAR(10) PRIMARY KEY,
teacher_name CHAR(10) NOT NULL,
teacher_contact CHAR(10) NOT NULL
) ENGINE=INNODB DEFAULT CHARSET=gbk;

CREATE TABLE class(
class_no int auto_increment PRIMARY KEY,
class_name CHAR(20) NOT NULL UNIQUE,
department_name CHAR(20) NOT NULL
)ENGINE=INNODB DEFAULT CHARSET=gbk;

CREATE TABLE course(
course_no int auto_increment PRIMARY KEY,
course_name CHAR(10) not NULL,
uplimit INT DEFAULT 60,
description text NOT NULL,
STATUSs CHAR(6) DEFAULT '未审核',
teacher_no CHAR(10) NOT NULL UNIQUE,
CONSTRAINT course_teacher_fk FOREIGN KEY (teacher_no) REFERENCES teacher(teacher_no)
)ENGINE=INNODB DEFAULT CHARSET=gbk;

CREATE TABLE student(
student_no CHAR(11) PRIMARY KEY,
student_name CHAR(10) NOT NULL,
student_contacts CHAR(20) NOT NULL,
class_no INT,
CONSTRAINT student_class_fk FOREIGN KEY(class_no) REFERENCES class(class_no)
)ENGINE=INNODB DEFAULT CHARSET=gbk;
CREATE TABLE choose(
choose_no INT auto_increment PRIMARY KEY,
student_no CHAR(11) NOT NULL,
course_no INT NOT NULL,
score TINYINT UNSIGNED,
choose_time datetime NOT NULL,
CONSTRAINT choose_student_fk FOREIGN KEY(student_no) REFERENCES student(student_no),
CONSTRAINT choose_course_fk FOREIGN KEY(course_no) REFERENCES course(course_no)
)ENGINE=INNODB DEFAULT CHARSET=gbk;

INSERT INTO course VALUES(NULL,'java',120,'none','shenhe','003');

复制一个表结构
CREATE TABLE today_copy LIKE today;
SHOW CREATE TABLE today_copy;
SELECT * from today_copy;

CREATE TABLE nowadays_cp SELECT * FROM nowadays;
SHOW CREATE TABLE nowadays_cp;
SELECT * FROM nowadays_cp;

修改表结构
ALTER TABLE persons DROP interest;
ALTER TABLE persons ADD person_no INT auto_increment PRIMARY KEY FIRST;
ALTER TABLE persons ADD person_name CHAR(10) NOT NULL;
ALTER TABLE persons ENGINE=myISam;
ALTER TABLE person RENAME human;
RENAME TABLE persons to person;

ALTER TABLE course MODIFY course_name CHAR(10) not NULL UNIQUE;//修改某一字段类型
ALTER TABLE course CHANGE course_name course_name CHAR(10) not NULL UNIQUE;

CREATE TABLE book(
isbn CHAR(20) PRIMARY KEY,
name1 CHAR(100) NOT NULL,
brief_intro text NOT NULL,
price DECIMAL(6,2),
publish_time date NOT NULL,
UNIQUE INDEX isbn_index (isbn),
INDEX NAME_index (name1(20)),
FULLTEXT INDEX brief_fulltext (name1,brief_intro),
INDEX complex_index (price,publish_time)
)ENGINE=myisam DEFAULT CHARSET=gbk;

插入索引
ALTER TABLE course ADD FULLTEXT INDEX descip_index(description);
CREATE FULLTEXT INDEX STATUSs_index ON course(STATUSs);

DROP INDEX STATUSs_index ON course;

删除唯一性约束
show INDEX FROM nowadays
ALTER TABLE course DROP INDEX course_name_2;
注意：如果该字段是外键，需要先删除外键，然后再删除唯一性约束。之后添加外键约束。
ALTER TABLE mytable DROP FOREIGN KEY mytable_ibfk_1 ;
ALTER TABLE course DROP INDEX course_name_2;
ALTER TABLE course ADD CONSTRAINT teacher_course_fk FOREIGN KEY(teacher_no) REFERENCES teacher(teacher_no)

插入结果集
INSERT INTO class_cp SELECT * FROM class;

替换掉目标记
REPLACE INTO class VALUES('1','zi','jidan');

UPDATE class SET department_name='xingong' WHERE class_no<3;

TRUNCATE TABLE class_cp1;
delete from table class_cp;//不重置自加器

SELECT DISTINCT department_name FROM class;

SELECT * FROM  class LIMIT 0,1;//查询0-1记录

A references B,A.key必须存在于B.key

//join
SELECT student_no,student_name,student_contacts,student.class_no ,class_name,department_name
FROM student JOIN class ON student.class_no=class.class_no;
SELECT student_no,student_name,student_contacts,s.class_no ,class_name,department_name
FROM  class AS c JOIN student AS s ON s.class_no=c.class_no;
SELECT student_no,student_name,student_contacts,s.class_no ,class_name,department_name
FROM  class AS c LEFT JOIN student AS s ON s.class_no=c.class_no;/*检索所有班级的学生信息*/
SELECT student_no,student_name,student_contacts,s.class_no ,class_name,department_name
FROM  class AS c  RIGHT JOIN student AS s ON s.class_no=c.class_no;/*检索所有学生的班级信息*/

查询所有学生的成绩，未选课依然会显示
SELECT student.student_no,student_name,course.course_no,course.course_name,choose.score
FROM student LEFT JOIN choose ON student.student_no=choose.student_no
LEFT JOIN course ON choose.course_no=course.course_no;

查询所有学生的成绩，未选课不会显示
SELECT student.student_no,student_name,course.course_no,course.course_name,choose.score
FROM student LEFT JOIN choose ON student.student_no=choose.student_no
inner JOIN course ON choose.course_no=course.course_no;

查询没选课的同学，不可用inner join
SELECT student.student_no,student_name,course.course_no,course.course_name,choose.score
FROM student LEFT JOIN choose ON student.student_no=choose.student_no
LEFT JOIN course ON choose.course_no=course.course_no
WHERE course.course_no IS NULL;

设置字符集
保持前后一致，否则会出现乱码
show variables like'character%';
SET CHARACTER_set_results=utf8;

SELECT student.student_no,student_name,course.course_no,course.course_name,choose.score
FROM student  left JOIN choose ON student.student_no=choose.student_no
left JOIN course ON choose.course_no=course.course_no
WHERE course.course_no IS NOT NULL AND course_name='java';

模糊查询
SELECT student.student_no,student_name,course.course_no,course.course_name,choose.score
FROM student  left JOIN choose ON student.student_no=choose.student_no
left JOIN course ON choose.course_no=course.course_no
WHERE course.course_no IS NOT NULL AND course_name LIKE 'j_';

按照学号排序，若学号同则按照课程排序
SELECT student.student_no,student_name,course.course_no,course.course_name,choose.score
FROM student  left JOIN choose ON student.student_no=choose.student_no
left JOIN course ON choose.course_no=course.course_no
WHERE course.course_no IS NOT NULL AND course_name LIKE 'j%'
ORDER BY   student.student_no ASC,course.course_no ASC;

聚合函数

SELECT COUNT(*) 学生人数 FROM student;
SELECT AVG(score) 总成绩 FROM choose
WHERE student_no=201113;
统计班级人数
SELECT class_name,COUNT(student_no) 人数
FROM class LEFT JOIN student ON student.class_no=class.class_no
GROUP BY class.class_no;

SELECT course_name 课程名称,COUNT(choose.student_no) 选课人数
FROM course LEFT JOIN  choose ON course.course_no =choose.course_no
GROUP BY course.course_name

SELECT choose.student_no 学号,student.student_name 姓名,AVG(score) 平均分
FROM student LEFT JOIN choose ON student.student_no=choose.student_no
GROUP BY student.student_no
HAVING AVG(score)>50;

SELECT class.class_name 班级,student.student_no 学号,GROUP_CONCAT(student.student_name) 姓名
FROM class LEFT JOIN student ON class.class_no=student.class_no
GROUP BY class.class_name;

SELECT class.class_no,COUNT(student.student_no)
FROM class LEFT JOIN student ON class.class_no=student.class_no
GROUP BY class.class_no WITH ROLLUP;

union all

子查询
SELECT student.student_no,student.student_name,class.class_name,course_name,score
FROM student LEFT JOIN class ON student.class_no=class.class_no
LEFT JOIN choose ON student.student_no=choose.student_no
LEFT JOIN course ON course.course_no=choose.course_no
WHERE score>(
SELECT AVG(score)
FROM choose INNER JOIN student ON choose.student_no=student.student_no
GROUP BY student_name
HAVING student_name='chuyao'
)

SELECT * FROM teacher
WHERE teacher_no NOT IN (
SELECT teacher.teacher_no FROM teacher JOIN course WHERE teacher.teacher_no=course.teacher_no
)

exists