LYNX

Links

Tags

Categories

mysql笔记

通用

建表

create table if not exists customers(
cid char(4) not null,
cname char(20) not null,
city char(20),
discnt real,
primary key ( cid )
) character set = utf8 -- 支持中文;

修改并查看注释(comment)

alter table customers
change column cid
cid char(4) not null comment '编号',
change column cname
cname char(20) not null comment '姓名',
change column city
city char(20) comment '城市',
change column discnt
discnt real comment '折扣';
show full columns from customers;

insert去重

  • ignore
insert ignore into table (column)
values
...
  • on duplicate key update

TODO

  • replace into

TODO

更新表数据

update table_name set item="shit" where fuck="fuck";

每组前n

参考

计算时间差

SELECT TIMESTAMPDIFF(MONTH,'2009-10-01','2009-09-01');
SELECT TIMESTAMPDIFF(MONTH,'2009-10-01','2009-09-01') as a;

其中MONTH部分可以更改为

  • SECOND
  • MINUTE
  • HOUR
  • DAY
  • MONTH
  • YEAR

其他

添加用户

insert

use mysql
insert into user ( Host, User, Select_priv, Insert_priv, Update_priv, Delete_priv, Create_priv, Drop_priv, Reload_priv, Shutdown_priv, Process_priv, File_priv, Grant_priv, References_priv, Index_priv, Alter_priv, Show_db_priv, Super_priv, Create_tmp_table_priv, Lock_tables_priv, Execute_priv, Repl_slave_priv, Repl_client_priv, Create_view_priv, Show_view_priv, Create_routine_priv, Alter_routine_priv, Create_user_priv, Event_priv, Trigger_priv, Create_tablespace_priv, ssl_type, ssl_cipher, x509_issuer, x509_subject, max_questions, max_updates, max_connections, max_user_connections, plugin, authentication_string, password_expired, password_last_changed, password_lifetime, account_locked )
values
('localhost', 'niabie', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', 'Y', '', '', '', '', 0, 0, 0, 0, 'mysql_native_password', password(''), 'N', '2019-11-07 15:17:00', null, 'N');
flush privileges;# 更新

用户具有创建数据库等的权限

create

参考

create user lynx;
update user set Host='localhost', authentication_string=password('1111') where User='lynx';
flush privileges;# 更新
grant all on database.table to 'lynx'@'localhost';# 分配database的table权限给用户
show grants for lynx@localhost;# 显示用户权限

用户没有创建数据库的权限

其他

  • 创建数据库并选择
create database homework3;
show databases;
use homework3;
show tables;
  • 查看版本等
select version();
select now();
select user();
  • 查看端口
show variables like 'port';

Tags

sql

Categories

1 / 1