创建数据库 

1 create database studentdb charset utf8;

1 #创建数据库 2 create database studentdb charset utf8; 3 #查看数据库的字符集 4 show create database studentdb; 5 #创建数据表 6 create table students( 7  id int auto_increment,     #int 代表数字类型，char 代表字符串类型 8  name char(32) not null,  #date 代表时间类型， not null 代表不能为空 9  age int not null,             #auto_increment 代表自增10  addr char(32),               #  primary key (id)   代表id 为主键11  register_date date not null,12  primary key (id));

#插入数据到表insert into students (name,age,register_date) values ("zhangchen",21,"2016-11-30");  #insert into 表名 （字段）values （字段对应的值）; #查询数据表 select * from students where id >3 and age >24; select * from students  limit 7 ;  #查询前7行 select * from students  limit 7 offset 2;   #从第3行起往后查7行    offset 默认为0 select * from students where register_date like "2016-09%";    #模糊查询

#修改表 update  students set name="xuxiaoyu" where age=22;   #update 表名 set [字段=值],[字段=值] where age = 22; delete from students where name = "liruixin";   #删除数据 select * from students order by register_date asc;   #order by 后边的字段按升序排序   select * from students order by register_date desc;   #order by 后边的字段按降序排序 select name,count(*) from students group by name;  #分组统计   统计这个表中相同名字的人数 #字段操作 alter table students add sex enum("M","F") not null;  增加一个字段 alter table students drop addr  #删除一个字段 alter table students modify sex enum("f","m") null;    alter table students modify age int(20);    #修改字段的属性

　　

连表查询

# A ， B 为两个表   a,b分别为A和B表的一个字段select * from A inner join B on A.a = B.b;   #查询A表和表的字段的交集select * from A left join B on A.a = B.b; #求两个表中两个字段的差集select * from A left join B on A.a = B.b union select * from A right join B on A.a = B.b; #查询两个表中字段的并集