1、修改root命令
mysqladmin -u root -p password [newpassword]
注意password 是修改密码的命令
2、远程登录
mysql -u root -h 127.0.0.1 -P 3306 -D demo -p
3、between包含首尾
select * from product where price between 5 and 10
价格在[5,10]，包括5和10
4、null值判断
select * from contract where contact_mobile is null
5、模糊匹配
select * from user where name like '%tom%'
%表示任意字符，任意次数
select * from user where name like '_tom'
_ 表示一个字符
6、连接字符串
select concat(name,'(',phone,')') from contract
7、去除字符串空格
select trim(phone) from contract
8、统计
select count(*) from product 包含空值
select count(phone) from product 不包含空值
9、分组
group by 默认约定
group by 子句中列出的每个列都必须是检索列 或者 有效的表达式（不能使聚集函数）
过滤分组
select user_id ,count(*) as orders from orders group by user_id having count(*) >=2
10、子查询作为select字段
select user_name,(select count(*) from orders where orders.user_id = customers.user_id) as orders
from customers
select user_name,(case when add_time > '2014-03-01' then 1 else 0 end) as flag from users
11、插入数据
插入多条
insert into action_detail(action_id,add_time,user_id) values(1,'2014-04-25',9090),(1,'2014-02-30',9090)
从select 中插入
insert into action_detail(action_id,add_time,user_id) select action_id,add_time,user_id from action
12、更新多个值
update product set name='123',phone='010-9890987' where id=9
