07. MybatisPlus查询封装类QueryWrapper比较api

简介：介绍MybaitsPlus核心查询条件类QueryWrapper的比较API讲解

• QueryWrapper介绍

  • 可以封装sql对象，包括where条件，order by排序，select哪些字段等等
  • 查询包装类，可以封装多数查询条件，泛型指定返回的实体类

  List<BannerDO> list = bannerMapper.selectList(new QueryWrapper<BannerDO>());
  

• 核心API

  • eq 等于
  • ne 不等于
  • gt 大于
  • ge 大于等于
  • lt 小于
  • le 小于等于
  • or 拼接or
  • between 两个值中间
  • notBetween 不在两个值中间

= ? AND != ?

@Test
@DisplayName("banner- = ? AND != ?")
public void test13() throws Exception {
    QueryWrapper queryWrapper = new QueryWrapper();
    queryWrapper.eq("img", "img3");
    queryWrapper.ne("url", "aaa.com");
    List<BannerDO> list = bannerMapper.selectList(queryWrapper);
    log.info("rows:{}",list);

}

= ? OR != ?

@Test
@DisplayName("banner- = ? OR != ?")
public void test14() throws Exception {
    QueryWrapper queryWrapper = new QueryWrapper();
    queryWrapper.eq("img", "img3");
    queryWrapper.or();
    queryWrapper.ne("url", "aaa.com");
    List<BannerDO> list = bannerMapper.selectList(queryWrapper);
    log.info("rows:{}",list);

}

链式调用

模糊查询

WHERE (url LIKE ? AND img NOT LIKE ?)

@Test
@DisplayName("banner- 模糊查询")
public void test15() throws Exception {
    QueryWrapper queryWrapper = new QueryWrapper();
    queryWrapper.like("url", "aaa.com");
    queryWrapper.notLike("img", "img3");
    List<BannerDO> list = bannerMapper.selectList(queryWrapper);
    log.info("rows:{}",list);

}

WHERE (url LIKE ? OR img NOT LIKE ?)

@Test
@DisplayName("banner- 模糊查询")
public void test16() throws Exception {
    QueryWrapper queryWrapper = new QueryWrapper();
    queryWrapper.like("url", "aaa.com");
    queryWrapper.or();
    queryWrapper.notLike("img", "img3");
    List<BannerDO> list = bannerMapper.selectList(queryWrapper);
    log.info("rows:{}",list);

}

WHERE (url LIKE ? OR img LIKE ?)

Parameters: %aaa.com(String), img3%(String)

@Test
@DisplayName("banner- 左、右模糊查询")
public void test17() throws Exception {
    QueryWrapper queryWrapper = new QueryWrapper();
    queryWrapper.likeLeft("url", "aaa.com");
    queryWrapper.or();
    queryWrapper.likeRight("img", "img3");
    List<BannerDO> list = bannerMapper.selectList(queryWrapper);
    log.info("rows:{}",list);

}

WHERE (img IS NULL AND url IN (?,?))

Parameters: aaa(String), bbbb(String)

@Test
@DisplayName("banner- WHERE (img IS NULL AND url IN (?,?))")
public void test18() throws Exception {
    QueryWrapper queryWrapper = new QueryWrapper();
    queryWrapper.isNull("img");
    queryWrapper.in("url",Arrays.asList("aaa","bbbb"));
    List<BannerDO> list = bannerMapper.selectList(queryWrapper);
    log.info("rows:{}",list);

}

WHERE (img IS NULL AND url IN (?,?)) ORDER BY id DESC

@Test
@DisplayName("banner-WHERE (img IS NULL AND url IN (?,?)) ORDER BY id DESC")
public void test18() throws Exception {
    QueryWrapper queryWrapper = new QueryWrapper();
    queryWrapper.isNull("img");
    queryWrapper.in("url",Arrays.asList("aaa","bbbb"));
    queryWrapper.orderByDesc("id");
    List<BannerDO> list = bannerMapper.selectList(queryWrapper);
    log.info("rows:{}",list);

}