Mybatis-plus各种查询方法_会飞地太阳_mybatisplus查询

大大的周 02-07 5838

mybatis-plus的基础查询方法：?

? @Test public void contextLoads() { } @Autowired private UserInfoMapper userInfoMapper; /** * 普通查询 */ @Test public void selectById() { UserInfo userInfo = userInfoMapper.selectById(123); System.out.println(userInfo); } /** * 批量查询 */ @Test public void selectByIds() { List<Long> ids = Arrays.asList(123L,124L,125L); List<UserInfo> userInfo = userInfoMapper.selectBatchIds(ids); System.out.println(userInfo); } /** * 名字包含娟并且年龄小于30 */ @Test public void selectByWrapper() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.like("username","娟").lt("age",30); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * 名字包含娟并且年龄大于等于20且小于等于40并且email不为空 */ @Test public void selectByWrapper2() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.like("username","娟").between("age",20,30).isNotNull("email"); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * 名字姓肖或者年量大于等于20，按照年龄降序排列，年龄相同按照id生序排列 */ @Test public void selectByWrapper3() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.likeRight("username","肖") .or().ge("age",20).orderByDesc("age").orderByAsc("id"); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * 创建日期为2019年10月2日并且直属上级名字为王姓 */ @Test public void selectByWrapper4() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.apply("date_format(create_time,'%Y-%m-%d')={0}","2019-10-02") .inSql("parent_id","select id from user where username like '王%'"); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } //上面的日期查询使用的是占位符的形式进行查询，目的就是为了防止SQL注入的风险 /** * 名字为王姓并且（年龄小于40或邮箱不为空） */ @Test public void selectByWrapper5() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.likeRight("username","王") .and(wq->wq.lt("age",40)) .or().isNotNull("email"); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * 名字为王姓并且（年龄小于40并且大与20或邮箱不为空） */ @Test public void selectByWrapper6() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.likeRight("username","王") .and(wq->wq.lt("age",40).gt("age",20)) .or().isNotNull("email"); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * （年龄小于40并且大与20或邮箱不为空）并且名字为王姓 */ @Test public void selectByWrapper7() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.nested(wq->wq.lt("age",40).gt("age",20)) .or().isNotNull("email") .likeRight("username","王"); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * 年龄23，30，40 */ @Test public void selectByWrapper8() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.in("age",Arrays.asList(20,30,40)); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * 只返回满足条件的其中一条语句即可 */ @Test public void selectByWrapper9() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.in("age",Arrays.asList(20,30,40)).last("limit 1"); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * 名字中包含雨并且年龄小于40(只取id,username) */ @Test public void selectByWrapper10() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.select("id","username").like("username","雨").lt("age",40); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * 名字中包含雨并且年龄小于40(不取create_time,parent_id两个字段,即不列出全部字段) */ @Test public void selectByWrapper11() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.like("username","雨").lt("age",40) .select(UserInfo.class,info->!info.getColumn().equals("create_time")&& !info.getColumn().equals("parent_id")); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * 姓名和邮箱不为空 */ public void testCondition() { String username = "王"; String email = ""; condition(username,email); } private void condition(String username,String email){ QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.like(StringUtils.isNullOrEmpty(username),"name",username) .like(StringUtils.isNullOrEmpty(email),"email",email); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * 实体作为条件构造器方法的参数 */ @Test public void selectByWrapperEntity() { UserInfo whereUser = new UserInfo(); whereUser.setUsername("xiaojuan"); whereUser.setAge(22); QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(whereUser); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * AllEq用法 */ @Test public void selectByWrapperAllEq() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); Map<String, Object> params = new HashMap<String, Object>(); params.put("nuserame","xiaojuan"); params.put("age",null); queryWrapper.allEq(params); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * AllEq用法(排除不是条件的字段) */ @Test public void selectByWrapperAllEq2() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); Map<String, Object> params = new HashMap<String, Object>(); params.put("nuserame","xiaojuan"); params.put("age",null); queryWrapper.allEq((k,v)->!k.equals("name"),params); List<UserInfo> userInfoList = userInfoMapper.selectList(queryWrapper); userInfoList.forEach(System.out::println); } /** * selectMaps */ @Test public void selectByWrapperMaps() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.like("name","肖").lt("age",40); List<Map<String,Object>> userInfoList = userInfoMapper.selectMaps(queryWrapper); userInfoList.forEach(System.out::println); } /** * 按照直属上级分组，查询每组的平均年龄，最大年龄，最小年龄。并且只取年龄总和小于500的组 */ @Test public void selectByWrapperMaps2() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.select("avg(age) avg_age","min(min) min_age","max(age) max_age") .groupBy("parent_id").having("sum(age)<{0}",500); List<Map<String,Object>> userInfoList = userInfoMapper.selectMaps(queryWrapper); userInfoList.forEach(System.out::println); } /** * selectObjs */ @Test public void selectByWrapperObjs() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.select("id","name").like("name","肖").lt("age",40); List<Object> userInfoList = userInfoMapper.selectObjs(queryWrapper); userInfoList.forEach(System.out::println); } /** * selectCount */ @Test public void selectByWrapperCount() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.like("name","肖").lt("age",40); Integer count = userInfoMapper.selectCount(queryWrapper); System.out.println(count); } /** * selectOne */ @Test public void selectByWrapperSelectOne() { QueryWrapper<UserInfo> queryWrapper = new QueryWrapper<UserInfo>(); queryWrapper.like("name","肖").lt("age",40); UserInfo user = userInfoMapper.selectOne(queryWrapper); System.out.println(user); } /** * 使用Lambda */ @Test public void selectLambda() { // LambdaQueryWrapper<UserInfo> lambda = new QueryWrapper<UserInfo>().lambda(); LambdaQueryWrapper<UserInfo> lambda = new LambdaQueryWrapper<UserInfo>(); lambda.like(UserInfo::getUsername,"娟").lt(UserInfo::getAge,40); List<UserInfo> userInfoList = userInfoMapper.selectList(lambda); userInfoList.forEach(System.out::println); } /** * 使用Lambda,名字为王姓（年龄小于40或邮箱不为空） */ @Test public void selectLambd2() { LambdaQueryWrapper<UserInfo> lambda = new LambdaQueryWrapper<UserInfo>(); lambda.like(UserInfo::getUsername,"娟") .and(lqw->lqw.lt(UserInfo::getAge,40).or().isNotNull(UserInfo::getEmail)); List<UserInfo> userInfoList = userInfoMapper.selectList(lambda); userInfoList.forEach(System.out::println); } /** * 使用Lambda链式 */ @Test public void selectLambd3() { List<UserInfo> userInfoList = new LambdaQueryChainWrapper<UserInfo>(userInfoMapper) .like(UserInfo::getUsername,"娟").ge(UserInfo::getAge,20).list(); userInfoList.forEach(System.out::println); } ?