You Need the Key Value of the Data You Just Inserted

Sometimes you need to use the auto_increment key value immediately after an INSERT. You may use it in another table, or expose the generated sequence number to the user.

MyBatis provides the useGeneratedKeys option for this purpose. With this option, you can get the generated key right after INSERT.

How to Use It

The declaration looks like this. Set useGeneratedKeys to true, and the value defined in keyProperty is mapped to a field in the corresponding class. In the table, article_id is the PK and is AUTO_INCREMENT.

<insert id="insertArticle" parameterType="com.example.madplay.model.Article" useGeneratedKeys="true"
        keyProperty="articleId" keyColumn="article_id">
    INSERT INTO article ( title, reg_date ) VALUES ( #{title}, NOW() )
</insert>

With this declaration, you can use it on the Java side as follows.

Article article = new Article();
article.setTitle("Title");

myMapper.insert(article);

// The `articleId` value is set in the object parameter used for `insert` execution.
System.out.println("articleId: " + article.getArticleId());

In the previous declaration, the parameter type was a Java class, but Map is also supported.

<insert id="insertArticle" parameterType="map" useGeneratedKeys="true"
        keyProperty="articleId" keyColumn="article_id">
    INSERT INTO article ( title, reg_date ) VALUES ( #{title}, NOW() )
</insert>

When you use Map, the result is also stored in the key defined by keyProperty.

Map<String, String> params = new HashMap<>();
params.put("title", "Title");

myMapper.insert(params);

// The `articleId` value is set in the Map parameter used for `insert` execution.
System.out.println("articleId: " + params.get("articleId"));