MyBatis-Plus Wrapper条件构造器查询大全

一、引言

那么那么那么今天来说下MP中强大的条件查询功能。

本章是基于上个案例来讲的：MyBaits-Plus 快速入门案例

二、具体操作

首先来说说基本的查询吧，根据主键或者简单的查询条件进行查询。

    /**
     * 通过单个ID主键进行查询
     */
    @Test
    public void selectById() {
        User user = userMapper.selectById(1094592041087729666L);
        System.out.println(user);
    }

    /**
     * 通过多个ID主键查询
     */
    @Test
    public void selectByList() {
        List longs = Arrays.asList(1094592041087729666L, 1094590409767661570L);
        List users = userMapper.selectBatchIds(longs);
        users.forEach(System.out::println);
    }

    /**
     * 通过Map参数进行查询
     */
    @Test
    public void selectByMap() {
        Map params = new HashMap<>();
        params.put("name", "张雨琪");
        List users = userMapper.selectByMap(params);
        users.forEach(System.out::println);
    }

MyBatis-Plus还提供了Wrapper条件构造器，具体使用看如下代码：

/**
     * 名字包含雨并且年龄小于40
     * 

     * WHERE name LIKE '%雨%' AND age < 40
     */
    @Test
    public void selectByWrapperOne() {
        QueryWrapper wrapper = new QueryWrapper();
        wrapper.like("name", "雨").lt("age", 40);
        List users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }

    /**
     * 名字包含雨
     * 年龄大于20小于40
     * 邮箱不能为空
     * 

     * WHERE name LIKE '%雨%' AND age BETWEEN 20 AND 40 AND email IS NOT NULL
     */
    @Test
    public void selectByWrapperTwo() {
        QueryWrapper wrapper = Wrappers.query();
        wrapper.like("name", "雨").between("age", 20, 40).isNotNull("email");
        List users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }

    /**
     * 名字为王性
     * 或者年龄大于等于25
     * 按照年龄降序排序，年龄相同按照id升序排序
     * 

     * WHERE name LIKE '王%' OR age >= 25 ORDER BY age DESC , id ASC
     */
    @Test
    public void selectByWrapperThree() {
        QueryWrapper wrapper = Wrappers.query();
        wrapper.likeRight("name", "王").or()
                .ge("age", 25).orderByDesc("age").orderByAsc("id");
        List users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }

    /**
     * 查询创建时间为2019年2月14
     * 并且上级领导姓王
     * 

     * WHERE date_format(create_time,'%Y-%m-%d') = '2019-02-14' AND manager_id IN (select id from user where name like '王%')
     */
    @Test
    public void selectByWrapperFour() {
        QueryWrapper wrapper = Wrappers.query();
        wrapper.apply("date_format(create_time,'%Y-%m-%d') = {0}", "2019-02-14")
                .inSql("manager_id", "select id from user where name like '王%'");
        List users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }

    /**
     * 查询王姓
     * 并且年龄小于40或者邮箱不为空
     * 

     * WHERE name LIKE '王%' AND ( age < 40 OR email IS NOT NULL )
     */
    @Test
    public void selectByWrapperFive() {
        QueryWrapper wrapper = Wrappers.query();
        wrapper.likeRight("name", "王").and(qw -> qw.lt("age", 40).or().isNotNull("email"));
        List users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }

    /**
     * 查询王姓
     * 并且年龄大于20 、年龄小于40、邮箱不能为空
     * 

     * WHERE name LIKE ? OR ( age BETWEEN ? AND ? AND email IS NOT NULL )
     */
    @Test
    public void selectByWrapperSix() {
        QueryWrapper wrapper = Wrappers.query();
        wrapper.likeRight("name", "王").or(
                qw -> qw.between("age", 20, 40).isNotNull("email")
        );
        List users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }

    /**
     * (年龄小于40或者邮箱不为空) 并且名字姓王
     * WHERE ( age < 40 OR email IS NOT NULL ) AND name LIKE '王%'
     */
    @Test
    public void selectByWrapperSeven() {
        QueryWrapper wrapper = Wrappers.query();
        wrapper.nested(qw -> qw.lt("age", 40).or().isNotNull("email"))
                .likeRight("name", "王");
        List users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }

    /**
     * 查询年龄为30、31、32
     * WHERE age IN (?,?,?)
     */
    @Test
    public void selectByWrapperEight() {
        QueryWrapper wrapper = Wrappers.query();
        wrapper.in("age", Arrays.asList(30, 31, 32));
        List users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }

    /**
     * 查询一条数据
     * limit 1
     */
    @Test
    public void selectByWrapperNine() {
        QueryWrapper wrapper = Wrappers.query();
        wrapper.in("age", Arrays.asList(30, 31, 32)).last("limit 1");
        List users = userMapper.selectList(wrapper);
        users.forEach(System.out::println);
    }