The writing of the trigger of Mysql

A trigger is a database object related to table operations. When a specified event occurs on the table where the trigger is located, the object will be called, that is, the operation event of the table triggers the execution of the trigger on the table.

 

1. Fixed format of trigger

create trigger triggerName
after/before insert/update/delete on table name
for each row #This sentence is a fixed
begin
sql statement in mysql;
end;

2. New record trigger
create trigger I_Tri_User1
after insert on user
for each row   
begin
insert into logs(content,action) value(new.name,'I');
end;

3. Delete record trigger
create trigger D_Tri_User1
after delete on user
for each row
begin
insert into logs(content,action) value(old. name,'D');
end;

4.
Create trigger U_Tri_User1
after update on user
for each row
begin
insert into logs(content,action) value(old.name,'U');
insert into logs(content,action) value(new.name,'U');
end;

 

 

Intermediate table creation statement

CREATE TABLE `logs` (
`id`  int(11) NOT NULL AUTO_INCREMENT ,
`content`  varchar(100)  ,
`action`  char(2)  ,
PRIMARY KEY (`id`)
);

 

CREATE TABLE `user` (
`id`  int(11) NOT NULL ,
`name`  varchar(20)   ,
`password`  varchar(20)   ,
`email`  varchar(20)  ,
`birthday`  datetime   ,
PRIMARY KEY (`id`)
)