详解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。

  
  @Test
  public void selectById() {
    User user = userMapper.selectById(1094592041087729666L);
    System.out.println(user);
  }

  
  @Test
  public void selectByList() {
    List longs = Arrays.asList(1094592041087729666L, 1094590409767661570L);
    List users = userMapper.selectBatchIds(longs);
    users.forEach(System.out::println);
  }

  
  @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：

  @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);
  }

  
  @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);
  }

  
  @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);
  }

  
  @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);
  }

  
  @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);
  }

  
  @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);
  }

  
  @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);
  }

  
  @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);
  }

  
  @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);
  }

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