网站新闻前置审批,网站编辑软件有哪些,建设个人博客网站制作,建设工程 法律 网站记录下MybatisPlus的简单的增删改查
接口概述 Service和Mapper区别
Mapper简化了单表的sql操作步骤#xff08;CRUD#xff09;#xff0c;而Serivce则是对Mapper的功能增强。 Service虽然加入了数据库的操作#xff0c;但还是以业务功能为主#xff0c;而更加复杂的SQL…记录下MybatisPlus的简单的增删改查
接口概述 Service和Mapper区别
Mapper简化了单表的sql操作步骤CRUD而Serivce则是对Mapper的功能增强。 Service虽然加入了数据库的操作但还是以业务功能为主而更加复杂的SQL查询还是要靠Mapper对应的XML文件里去编写SQL语句
常用增删改查
查询所有数据 /*** 查询所有数据*/GetMapping(/getUserList)public ListTrainUserEntity getUserList() {return trainUserService.list();}根据id查询 /*** 根据id查询数据*/GetMapping(/getUserById)public TrainUserEntity getUserById(RequestParam String id) {return trainUserService.getById(id);}根据条件查询 /*** 使用LambdaQueryWrapper查询指定年龄的人员*/Overridepublic ListTrainUserEntity getUserByAge(String age) {LambdaQueryWrapperTrainUserEntity userEntityLambdaQueryWrapper new LambdaQueryWrapper();userEntityLambdaQueryWrapper.eq(TrainUserEntity::getAge, age);ListTrainUserEntity list trainUserMapper.selectList(userEntityLambdaQueryWrapper);return list;}使用exists查询
查询有所属部门的人员 public ListTrainUserEntity getUserInfo() {LambdaQueryWrapperTrainUserEntity wrapper new LambdaQueryWrapper();wrapper.exists(SELECT 1 FROM DEPT WHERE DEPT.DID USER.DEPTID);ListTrainUserEntity userVOList trainMapper.selectList(wrapper);return userVOList;}生成的SQL
SELECT id,name,age,address,deptid FROM user WHERE (EXISTS (SELECT 1 FROM DEPT WHERE DEPT.DID USER.DEPTID))使用xml查询 新增 /*** 新增** param trainUserEntity 需要插入的数据* return 是否成功*/PostMapping(/saveUser)public boolean saveUser(RequestBody TrainUserEntity trainUserEntity) {return trainService.save(trainUserEntity);}/*** 新增数据*/Overridepublic boolean add(TrainUserEntity trainUserEntity) {return trainMapper.add(trainUserEntity);}删除 /*** 根据主键id删除一条数据** param id 主键id* return 是否成功*/PostMapping(/removeById)public boolean deleteById(RequestParam String id) {return trainService.removeById(id);}/*** 根据主键id删除一条数据** param id 主键id* return 删除数据的条数*/Overridepublic int deleteById(String id) {LambdaQueryWrapperTrainUserEntity userEntityLambdaQueryWrapper new LambdaQueryWrapper();userEntityLambdaQueryWrapper.eq(TrainUserEntity::getId, id);int result trainMapper.delete(userEntityLambdaQueryWrapper);return result;}修改 /*** id修改一条数据** param trainUserEntity 需要修改的数据* return 修改结果*/PostMapping(/updateUser)public boolean updateUser(RequestBody TrainUserEntity trainUserEntity) {return trainService.updateById(trainUserEntity);}/*** 根据id更新实体数据*/Overridepublic int modifyById(TrainUserEntity trainUserEntity) {LambdaUpdateWrapperTrainUserEntity updateWrapper new LambdaUpdateWrapper();updateWrapper.eq(TrainUserEntity::getId, trainUserEntity.getId()).set(TrainUserEntity::getName, trainUserEntity.getName()).set(TrainUserEntity::getAddress, trainUserEntity.getAddress());int result trainMapper.update(null, updateWrapper);return result;}
