MySQL中 ON DUPLICATE KEY UPDATE语法的使用

MySQL ON DUPLICATE KEY UPDATE 为Mysql特有语法

ON DUPLICATE KEY UPDATE 用法与说明 

Mysql中INSERT ... ON DUPLICATE KEY UPDATE的实践

INSERT ... ON DUPLICATE KEY UPDATE语句

使用范例：

数据库当前存在id为20的记录，这时insert  id = 20 的记录会报错：

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的改进：存在则更新，不存在则插入

范例：

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)

执行结果： 

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

可以看到原始数据进行了更新： 

Mybatis 中使用范例：

======>>    其中 id,system_id为联合索引

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<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>