Msyql常用命令

授权超级用户：

grant all privileges on *.* to 'tangnanbing'@'%' identified by '1qaz@WSX' with grant option;

查看库：

show databases;

查看某个库的表

use db; show tables \G; 

查看表的字段

desc tb;

查看建表语句

show create table tb;

当前是哪个用户

select user();

当前库

select database();

创建库

create database db1; 

创建表

create table t1 (id int, name char(40) adress varchar(30));  
char(10) 'aaa '
varchar(10) 'aaa'

查看数据库版本

select version(); 

查看mysql状态

show status;

修改mysql参数

show variables like 'max_connect%'; set global max_connect_errors = 1000; 

查看mysql队列

show processlist; 
select * from information_schema.processlist where info is not null;

sleep的可以忽略，qurey查询的才有

创建普通用户并授权

grant all on *.* to databases1.user1 identified by '123456'; 
grant all on db1.* to 'user2'@'10.0.2.100' identified by '111222'; 
grant all on db1.* to 'user3'@'%' identified by '231222';insert into tb1 (id,name) values(1,'aming');

更改密码

UPDATE mysql.user SET password=PASSWORD("newpwd") WHERE user='username' ;   

查询

select count(*) from mysql.user; select * from mysql.db; select * from mysql.db where host like '10.0.%'; 

插入

update db1.t1 set name='aaa' where id=1;  

清空表

 truncate table db1.t1; 

删除表

drop table db1.t1; 

删除数据库

drop database db1; 

修复表

repair table tb1 [use frm];

查看权限

show grants for root@'localhost';
echo "select user,host,password from mysql.user" |mysql -uroot -plingxiangxiang
mysql -uroot -p1234556 -e "select user,host,password into outfile '/home/mysql/1.txt' from mysql.user;"

增：

insert into test.test (id, name) values (123, 'ling');
insert into test.test values (value1_1, value2_2), (value2_1,value2_2), (value3_1, value3_2);

删：

delete from test.test where id in (123, 456);
alter table test drop column dt;删除字段，test表，dt字段

改：

update msyql.user set password = password('lingxiangxiang')
alter table employees add primary key (emp_no); 增加主键
alter table employees drop/add column salaries; 删除字段
create table blog_blogmodel as select * from book_blogmodel; 创建一样的新表

查：

select user, host, password from mysql.user where user = "root";
select * from msyql.user where conditions order by user [desc];

调整字段顺序：

1.  ALTER TABLE `user_movement_log` CHANGE `GatewayId` `GatewayId` int not null default 0 AFTER RegionID  
2.  alter table test2 drop column cj, drop column goushi;

排序：

select * from test.test order by id asc/desc;
SELECT * FROM usersWHERE email NOT REGEXP '^[A-Z0-9._%-]+@[A-Z0-9.-]+.[A-Z]{2,4}$'
show global variables like '%read_only%';
alter user root@localhost identified by '';

导出：

select * into outfile '/tmp/test/users.txt' fields terminated by '<[!]>' lines terminated by '<[end]>' from users;

导入：

load data infile '/tmp/test/users.txt' into table gamedb.users fields terminated by '<[!]>' lines terminated by '<[end]>';
create index idx_name on salaries(emp_no); 创建salaries表的emp_no字段的索引
show index from salaries\G; 查看索引

日期常用格式：'year-month-day'

复杂语句：

select * from (select * from employees order by emp_no desc) aa group by hire_date ;

先对emp_no 进行反向排序，然后在把hire_date分组

image.png

内连接：join默认是inner

select * from employees inner join salaries on employees.emp_no = salaries.emp_no;

image.png

左外链接：右外链：

select * from employees left join salaries on employees.emp_no = salaries.emp_no;

image.png

select * from employees right join salaries on employees.emp_no = salaries.emp_no;  

image.png

update的加强版

select * from employees;

image.png

UPDATE `employees`
    SET emp_name = CASE emp_name
            WHEN 'ling' THEN 'lingjing'
            WHEN 'xiang' THEN 'lingxiang'
            ELSE 'wang'
            END
    WHERE gender='M';

image.png

limit 1 ：打印一行

max（emp_no）： 最大

select max(emp_no) as emp_no from employees; max(emp_no)改成名字emp_no

问题三：内联结 + 非关联子查询

SELECT s1.article, dealer, s1.price

FROM `shop` AS s1

    JOIN (  SELECT `article`, MAX(price) AS price

                FROM `shop`

                GROUP BY `article`

        ) AS s2

    ON s1.article = s2.article

        AND s1.price = s2.price

;