mysql uses on duplicate key update to update data in batches

Create Test—book Chart of Accounts

CREATE TABLE `book` (`id` int NOT NULL AUTO_INCREMENT,`unique_code` varchar(30) NOT NULL,`book_name` varchar(20) DEFAULT NULL,PRIMARY KEY (`id`),UNIQUE KEY `unique_code` (`unique_code`) USING BTREE COMMENT 'book unique_code') ENGINE=InnoDB AUTO_INCREMENT=3 DEFAULT CHARSET=utf8;

The premise requires that there is an index in the table: as follows unique_code is the index

Requirements:Data needs to be imported into the book table.When there is account data in the book table, update the data value, otherwise insert inserts a new record.

Previous practice: circularly select whether the booke record in the table exists, use update if it exists; use insert if it does not exist.
Disadvantages of practice: Each record needs to be operated twice (select, update/insert)

Optimization: use the insert statement with on duplicate key update.
Practice Note: For example, for the above requirements, you need to use book table**** uniqueunique_code index

I. Execute the following command

insert into book(unique_code,book_name) values ​​('zs-001','Chinese') on duplicate key update book_name='math';

2. Execute the command in step 1 again and you will find that the value of book_name has changed

Simple and easy to understand~~

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