ON DUPLICATE KEY UPDATE for MySQL operation

overview

ON DUPLICATE KEY UPDATE is mainly used for insert and update operations together. When a piece of data is inserted, the insert operation or update operation will be selected according to the primary key constraint and unique constraint. You can also do batch insert or update operations.

• When the primary key is duplicated, perform the Update operation
• When the primary key is not repeated and the unique constraint field is repeated, perform the Update operation
• When the primary key is not repeated and the unique constraint field is not repeated, perform the Insert operation

grammar

Can also do batch processing

INSERT INTO table(colum1,colum2,colum3...) VALUES (value1,value2,value3...)
ON DUPLICATE KEY UPDATE 
colum1 = value1, colum2 = value2, colum3 = value3 ... 

example

user table

id is the primary key, code has a unique constraint

insert three records

insert into 
`user` (id,code,age,username,password)
values (11,'aa',18,'zhangsan','123'),
(12,'bb',18,'lisi','123'),
(13,'cc',18,'wangwu','123');

Execute the operation
ps: the update operation did not modify the id

insert into 
`user` (id,code,age,username,password) 
values (11,'aa',18,'zhangsan','123'),
(120,'bb',18,'lisi','123456'),
(13,'cc',18,'wangwu','123456'),
(14,'dd',18,'laoliu','123')
as temp 
on duplicate key update
code = temp.code,age = temp.age,username = temp.username,password = temp.password;

Note: here the user zhangsan has not changed, lisi has changed the id and password, wangwu has changed the password, and added a new user record laoliu

Result

zhangsan did not change
lisi password change
wangwu password change
lailiu added successfully