The use of ON DUPLICATE KEY UPDATE syntax in MySQL

MySQL ON DUPLICATE KEY UPDATE is a unique syntax for Mysql

ON DUPLICATE KEY UPDATE usage and instructions 

Practice of INSERT...ON DUPLICATE KEY UPDATE in Mysql

INSERT ... ON DUPLICATE KEY UPDATE语句

Usage example:

There is currently a record with id 20 in the database. At this time, the record with insert id = 20 will report an error:

INSERT INTO `book`.`book_test` (`id`, `book_name`, `isbn`, `author`, `price`, `publisher`, `publish_date`, `is_sale`) VALUES ('20', '博弈论', '56', '刘一手', '52.00', '测试出版社', '2018-12-06', '1');

[SQL]INSERT INTO `book`.`book_test` (`id`, `book_name`, `isbn`, `author`, `price`, `publisher`, `publish_date`, `is_sale`) VALUES ('20', '博弈论', '56', '刘一手', '52.00', '测试出版社', '2018-12-06', '1');
[Err] 1062 - Duplicate entry '20' for key 'PRIMARY'

SQL improvements: update if it exists, insert if it doesn't exist

example:

INSERT INTO `book`.`book_test` (
	`id`,
	`book_name`,
	`isbn`,
	`author`,
	`price`,
	`publisher`,
	`publish_date`,
	`is_sale`
)
VALUES
	(
		'20',
		'博弈论',
		'56',
		'刘一手',
		'100.00',
		'测试出版社',
		'2018-12-06',
		'1'
	) ON DUPLICATE KEY UPDATE book_name =
VALUES
	(book_name),
	isbn =
VALUES
	(isbn),
	author =
VALUES
	(author),
	price =
VALUES
	(price),
	publisher =
VALUES
	(publisher),
	publish_date =
VALUES
	(publish_date),
	is_sale =
VALUES
	(is_sale)

Results of the: 

[SQL]INSERT INTO `book`.`book_test` (
...
VALUES
	(is_sale)
受影响的行: 2
时间: 0.001s

You can see that the original data has been updated: 

Examples of use in Mybatis:

======>> where id and system_id are joint indexes

<insert id="insertOrUpdate" parameterType="com.company.xxx.model.MyTestBean">
        insert into ${tableName}
        <trim prefix="(" suffix=")" suffixOverrides=",">
            <if test="systemId != null">
                system_id,
            </if>
            <if test="id != null">
                id,
            </if>
            <if test="order != null">
                order,
            </if>
            <if test="desc != null">
                desc,
            </if>
        </trim>
        <trim prefix="values (" suffix=")" suffixOverrides=",">
            <if test="systemId != null">
                #{systemId,jdbcType=INTEGER},
            </if>
            <if test="id != null">
                #{id,jdbcType=BIGINT},
            </if>
            <if test="order != null">
                #{order,jdbcType=VARCHAR},
            </if>
            <if test="desc != null">
                #{desc,jdbcType=LONGVARCHAR},
            </if>
        </trim>
        ON DUPLICATE KEY UPDATE
    <trim suffixOverrides=",">
        <if test="order != null">order=VALUES(order),</if>
        <if test="desc != null">desc=VALUES(desc),</if>
    </trim>
</insert>