获取刚刚 插入的自增主键

一、插入记录

需求：新增一个博客记录

mapper

    <insert id="insertBlog" parameterType="Blog">

        INSERT INTO `blog` (

          `title`,

          `author_id`,

          `state`,

          `featured`,

          `style`

        ) 

        VALUES

          (

            #{title},

            #{authorId},

            #{state},

            #{featured},

            #{style}

          )

    </insert>

接口：

int insertBlog(Blog blog);

测试：

    @Test

    public void testInsertBlog() {

        

        SqlSession session = MyBatisUtil.getSqlSession();

        BlogMapper blogMapper = session.getMapper(BlogMapper.class);

        

        Blog blog = new Blog();

        int count = blogMapper.insertBlog(blog);

        

        session.commit();

        session.close();

        

        System.out.println(blog);//看看是否有id值

        System.out.println("插入了" + count + "条记录");

    }

二、获取自增id

方式一：在mapper中配置 insert节点的属性 useGeneratedKeys="true" keyProperty="id"

mapper

    <insert id="insertBlog" parameterType="Blog" useGeneratedKeys="true" keyProperty="id">

        INSERT INTO `blog` (

          `title`,

          `author_id`,

          `state`,

          `featured`,

          `style`

        ) 

        VALUES

          (

            #{title},

            #{authorId},

            #{state},

            #{featured},

            #{style}

          )

    </insert>

方式二：在全局配置文件中配置 settings选项

    <settings>

        <setting name="useGeneratedKeys" value="true" />

    </settings>

并且在mapper的insert节点配置属性 keyProperty="id"

方式三：适用于没有自增主键的数据库

oracle版本

    <insert id="insertBlogOracle" parameterType="Blog">

        <selectKey resultType="java.lang.Integer" order="BEFORE" keyProperty="id">

            select seq.nextval as id from dual

        </selectKey>

        INSERT INTO `blog` (

          `title`,

          `author_id`,

          `state`,

          `featured`,

          `style`

        ) 

        VALUES

          (

            #{title},

            #{authorId},

            #{state},

            #{featured},

            #{style}

          )    

    </insert>

mysql版本：

    <insert id="insertBlogMysql" parameterType="Blog">

        <selectKey resultType="java.lang.Integer" order="AFTER" keyProperty="id">

            SELECT LAST_INSERT_ID()

        </selectKey>

        INSERT INTO `blog` (

          `title`,

          `author_id`,

          `state`,

          `featured`,

          `style`

        ) 

        VALUES

          (

            #{title},

            #{authorId},

            #{state},

            #{featured},

            #{style}

          )    

    </insert>