Mybatis动态SQL之IF语句详解

    //   查询博客
    List<Blog> queryBlogIf(Map map);

    <select id="queryBlogIf" parameterType="map" resultType="Blog">
        select * from mybatis.blog where 1=1
        <if test="title != null">
            and title = #{title}
        </if>
        <if test="author != null">
            and author = #{author}
        </if>
    </select>

    //    第一种情况,不加任何查询条件,默认会把所有数据查出来
    @org.junit.Test
    public void test01() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        BlogMapper mapper = sqlSession.getMapper(BlogMapper.class);
        Map map = new HashMap();
        List<Blog> blogs = mapper.queryBlogIf(map);
        for (Blog blog : blogs) {
            System.out.println(blog);
        }
    }

    @org.junit.Test
    public void test01() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        BlogMapper mapper = sqlSession.getMapper(BlogMapper.class);
        Map map = new HashMap();
        map.put("title", "Spring");
        List<Blog> blogs = mapper.queryBlogIf(map);
        for (Blog blog : blogs) {
            System.out.println(blog);
        }
    }

    @org.junit.Test
    public void test01() {
        SqlSession sqlSession = MybatisUtils.getSqlSession();
        BlogMapper mapper = sqlSession.getMapper(BlogMapper.class);
        Map map = new HashMap();
        map.put("title", "微服务");
        map.put("author", "天天天");
        List<Blog> blogs = mapper.queryBlogIf(map);
        for (Blog blog : blogs) {
            System.out.println(blog);
        }
    }