pymysql:

  - 连接、关闭（游标）

  - execute()   -- SQL注入    sss‘ or 1=1 --

  - 增删改： conn.commit()

  - fetchone fetchall

  - 获取插入数据自增ID 转储SQL文件

 命令行：

  mysqldump

  

  数据备份: 数据表结构+数据

   mysqldump -u 用户名  已有的数据库名 > 要转成的数据库名 -p

  

  数据备份：数据表结构

   mysqldump -u root -d db1 > db1.sql -p

   

  导入数据库：

   create database XX；

   mysqldump -u root -d XX < db1.sql -p

    # 查询课程大于60   

-- select * from score where num>60;

# 查询课程

-- select *from course;

# 查询任课老师

-- select * from course left join teacher no course.teacher_id = teacher.id;

# 查询学生对应的班级

-- select * from student left join class on student.class_id = class.id;

# 统计学生性别人数

-- select gender count(nid) from  sudent GROUP BY gender;

临时表:

 select num, course_id from (select num , course_id from score where num > 60) as B

 

 

 

 

 

查：

 in not in

 between and

 limit

 group by

 order by

 like "%a"

 left join xx on

 临时表：

  select * from (select * from tb where id < 10) as B

 

 select id,name,1,(select count(1) from tb) from tb2;

  

 select

  student_id ,

  select num from score as s2 where s2.student_id=s1.student_id and course_id= 1) as 语文,

  select num from score as s2 where s2.student_id = s1.student_id and course_id = 2) as 数学,

  select num from score as s2 where s2.student_id = s1.student_id and course_id = 3) as 英语

 from score as s1;