Mysql database user management

One 、 Data table operation

1.1 Clone table

Generate the data records of the table into a new table

# adopt  LIKE  Method , Copy  lyong  Table structure generation  lyong_bak  surface 
create table lyong_bak like lyong;		
# Import data 
insert into lyong_bak (select * from lyong);	   # Backup data content 

There is no data in the table after backup , Just cloned the structure of the table

take xy The data in is cloned into the backup xy_bak In the table

Method 2 、 Import content when creating

create table lyong_bak02 (select * from lyong);

# Get the table structure of the data table 、 Index and other information 
show create table lyong_bak\G;

1.2 Clear the table

Delete all data in the table

1.2.1deldte Delete

DELETE After emptying the table , There are deleted record entries in the returned result ;DELETE When working, delete record data line by line ; If there is a self growing field in the table , Use DELETE FROM After deleting all records , The newly added record will be changed from the original largest record ID Continue to write the record automatically later .

#delete from  Table name ;
delete from lly;
 
insert into lly(student_name,cardid,hobby) values('xyz',123456789,' nanjing ')
    -> ;

1.2.2 truncate Delete

TRUNCATE After emptying the table , No deleted entries are returned ;TRUNCATE When working, the table structure is rebuilt as it is , So in terms of speed TRUNCATE than DELETE Empty the watch, quick ; Use TRUNCATE TABLE After clearing the data in the table ,ID From 1 Start re recording .

truncate table info;
 
insert into lly(student_name,cardid,hobby) values('llly',654321,' Shanghai ');

1.2.3 Create a temporary table

After the temporary table is created successfully , Use SHOW TABLES The command cannot see the created temporary table , The temporary table will be destroyed after the connection exits .
If before exiting the connection , You can also perform operations such as adding, deleting, modifying, and querying , For example, use DROP TABLE Statement to manually and directly delete the temporary table .

## Add temporary table lyong01
create temporary table lyong01 (
id int(4) zerofill primary key auto_increment,
name varchar(10) not null,
cardid int(18) not null unique key,
hobby varchar(50));
 
##  View all tables in the current library 
show tables;	
## Add data to temporary table 
insert into test03 values(1,'zhangsan',123456789,'watch a film');	
## View all data in the current table 
select * from lyong01;
## Exit database 
quit						
 
## Log in again and view 		
mysql -u root -p
## View all data in the temporary table created before , Found to have been automatically destroyed 
select * from lyong01;			

Two 、 User management

2.1 A new user

CREATE USER ‘ user name ’@‘ Source address ’ [IDENTIFIED BY [PASSWORD] ‘ password ’];
‘ user name ’： Specify the user name that will be created

‘ Source address ’： Specify which hosts the newly created user can log on to , You can use IP Address 、 Network segment 、 The form of host name , Available to local users localhost, Allow any host to log in. Wildcards are available %

‘ password ’：

If plaintext password is used , Direct input ’ password ’, Inserted into the database by Mysql Automatic encryption ;

If you use an encrypted password , You need to use it first SELECT PASSWORD(‘ password ’); Get ciphertext , Then add... To the statement PASSWORD ‘ Ciphertext ’;

If you omit “IDENTIFIED BY” part , Then the user's password will be empty （ Not recommended ）

2.1.1 Create user using plaintext

CREATE USER 'liy'@'localhost' IDENTIFIED BY '123456';

2.1.2 Use ciphertext to create users

select password(‘123456’);
create user ‘zxy’@‘localhost’ identified by password ‘*E56A114692FE0DE073F9A1DD68A00EEB9703F3F1’;

View user information
The created user is saved in mysql Database user table
use mysql
select user,authentication_string,host from user;

2、 View user information

use mysql;
select User,authentication_string,Host from user;

3、 Rename user

rename user 'sxy'@'localhost' to 'shixy'@'localhost';
 
select user,authentication_string,host from user;

4、 Delete user

drop user 'shixy'@'localhost';
 
select user,authentication_string,host from user;

3、 ... and 、 Database user authorization

1、 Grant authority

GRANT sentence ： It is specially used to set the access rights of database users . When the specified user name does not exist ,GRANT Statement will create a new user ; When the specified user name exists ,GRANT Statement is used to modify user information .

GRANT  Permission list  ON  Database name . Table name  TO ' user name '@' Source address ' [IDENTIFIED BY ' password '];

Permission list ： Used to list various database operations authorized for use , Separated by commas , Such as “select,insert,update”. Use “all” Indicates all permissions , You can authorize any operation .
Database name . Table name ： The name of the database and table used to specify the authorization operation , You can use wildcards “”. for example , Use “kgc.” The object representing the authorization operation is kgc All the tables in the database .
‘ user name @ Source address ’： Used to specify the user name and the client address to which access is allowed , Who can connect 、 Where can I connect . The source address can be a domain name 、IP Address , You can also use “%” wildcard , Represents all addresses in an area or network segment , Such as “%.accp.com”、“192.168.80.%” etc. .
IDENTIFIED BY： Used to set the password string used by users when connecting to the database . When creating a new user , If you omit “IDENTIFIED BY” part , Then the user's password will be empty .

2、 Database authorization

show grants for [email protected];
# View user permissions 

Specify which database users can view / surface , No access to other databases

grant select on test.* to [email protected];
# user yong Only test Query permission of all tables under the library