[MySQL must know and know] trigger | permission management

trigger

For manual operation of data , It's easy to forget one step , Cause data loss .

Trigger operation

--  Create Syntax 
CREATE TRIGGER  Trigger Name  {BEFORE|AFTER} {
   INSERT|UPDATE|DELETE} 
ON  Table name  
FOR EACH ROW  expression ;

• Table name ： Represents the object monitored by the trigger .
• INSERT|UPDATE|DELETE： Indicates the event triggered .INSERT Indicates that... Is triggered when a record is inserted ;UPDATE Indicates that... Is triggered when the record is updated ;DELETE Indicates that... Is triggered when a record is deleted .
• BEFORE|AFTER： Indicates the trigger time .BEFORE Indicates that... Is triggered before the event ;AFTER In the event of Trigger later .

 --  Check triggers 
SHOW TRIGGERS \G;

--  Delete trigger 
drop trigger  Trigger Name ;

• If the trigger is executed , Statement error , Then it won't execute .

Advantages and disadvantages of flip flops

advantage

• Triggers ensure data integrity , The data is consistent , There will be no contradiction .
• Triggers can help us log operations
• Triggers can also be used before manipulating data , Check the validity of the data .
  shortcoming
• One of the biggest problems with triggers is poor readability , If an error occurs , Its error information is particularly difficult to find , It is basically similar to ordinary , Maintenance costs are high , The solution is to maintain a complete database design document .

Rights management

• user ： Personnel role ： A collection of permission assignments
• Appropriate permission settings , It can ensure the security of data , This is crucial .

role

• The role is in MySQL 8.0 New features introduced in , Equivalent to a collection of permissions . The purpose of introducing roles is to facilitate management Manage users with the same permissions .
• After creating the role , By default, this role does not have any permissions , We need to authorize the role .

--  Create the role   The role of   In single quotation marks 
create role role_id
CREATE ROLE 'manager'@'localhost';  
--  Role name is “manager”, The host that the role can log in   yes “localhost”
--  If you don't write the hostname ,MySQL  The default is wildcard “%”, This means that this account can be logged on from any host   Record database .

--  Authorize roles 
grant  jurisdiction  on  Table name  to  The role of ;   
select  read-only    
select,insert,delete,update  Additions and deletions 

--  View role permissions 
show grant for  Character name ;

--  Delete the role 
drop role  role id;

--  Activate role 
set global  activate_all_roles_on_login=ON;

• MySQL Created in After the role , The default is not activated , It needs to be activated before it can be assigned to the user .

user

--  Create user   You must specify a password 
CREATE USER  user name  [IDENTIFIED BY  password ];

--  Authorize users 
grant role_id to user_id;  --  You can create the permission of the role above   Assign to user 
grant  jurisdiction  on  Table name  to user_id; --  Direct empowerment 

--  View user permissions 
show grant for user_id;

--  Delete user  
drop user user_id;

Summary

• Roles are sets of permissions . Delete The character , Then the user will lose all the permissions obtained through this role
• When the character was just created , The default is not activated , You need to activate... Manually , Can only be Use .
• Try to use the database's own role and user mechanism To control access rights , Don't use it easily Root account number .