MySQL batch update

Article Directory

• • • Disadvantages of direct update
    • Method one; replace into
    • Method 2: insert into [table] values… on duplicate key update
    • Method 3: Create a temporary table
    • Method 4: Use MySQL's own batch update statement

Disadvantages of direct update

I recently made a request to update 3w pieces of data, one by one, and it took 80 minutes to update, which is very poor in performance and easy to block, so I found some ways to update MySQL in batches and record it here

Method one; replace into

This update will update other fields to default values, because it deletes duplicate records before updating, use with caution

replace into `user` (id,age) values ​​(1,'2'),(2,'3'),(3,'4'),(4,'98');-- > Time: 0.038s

Method 2: insert into [table] values… on duplicate key update

This method should also delete the record and then update it, but save the original data of other fields, so other fields will not change

insert into `user`(id,age) values ​​(1,'5'),(2,'7'),(3,'2'),(4,'198') on duplicatekey update age=values(age)-- > > Time: 0.017s

Method 3: Create a temporary table

Create a temporary table, insert the updated data into the temporary table, and then perform the update, you need to have the permission to create a table

DROP TABLE if EXISTS tmp;-- > Time: 0.016screate temporary table tmp(id int(4) primary key,age varchar(50));-- > Time: 0.01sinsert into tmp values ​​(1,'13'), (2,'16'),(3,'18'),(4,'18');-- > Time: 0.009supdate `user`, tmp set `user`.age=tmp.age where `user`.id=tmp.id;-- > Time: 0.022s

Method 4: Use MySQL's own batch update statement

update `user`set age = CASE idWHEN 1 THEN '22'WHEN 2 THEN '22'WHEN 3 THEN '22'WHEN 4 THEN '22'END WHERE id IN(1,2,3,4);-- > Time: 0.015supdate (tablename)set (updated field) = case (updated field)when (updated field value) then (updated field value)...end where (updated field) in((updated field value)...)

Example: set age = CASE id WHEN 1 THEN '22'
In simple terms, id is used as the query condition, and age=22 is updated when id=1. The where statement improves the execution of sqlEfficiency, first filter the records that need to be modified and then update.

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