🍁 作者：知识浅谈，CSDN签约讲师，CSDN博客专家，华为云云享专家，阿里云专家博主
📌 擅长领域：全栈工程师、爬虫、ACM算法
💒 公众号：知识浅谈
🔥网站：vip.zsqt.cc

✅MybatisPlus结合groupby实现分组和sum求和
这次使用的是LambdaQueryWrapper，使用QueryWrapper相对来说简单点就不写了

🎈实现GroupBy分组

第一步: 实体类中新增一个字段count

@TableName(value ="user")
@Data
public class User implements Serializable {@TableId(type = IdType.AUTO)private Integer id;@TableField(value = "name")private String name;@TableField(value = "age")private Integer age;@TableField(value = "state")private String state;@TableField(exist = false)private static final long serialVersionUID = 1L;//这个地方@TableField(value = "count(*)",insertStrategy = FieldStrategy.NEVER,updateStrategy = FieldStrategy.NEVER)private  Integer count;
}

第二步：查询接口中修改

   @GetMapping("/count")public List<User> count(){new QueryWrapper<>()LambdaQueryWrapper<User> queryWrapper = new LambdaQueryWrapper<>();queryWrapper.select(User::getState,User::getCount);queryWrapper.groupBy(User::getState);List<User> list = userService.list(queryWrapper);return list;}

返回的结果

[{"id": null,"name": null,"age": null,"state": "1","count": 3},{"id": null,"name": null,"age": null,"state": "2","count": 2}
]

🎈实现GroupBy分组之后再sum求和

第一步: 实体类中新增一个字段count

@TableName(value ="user")
@Data
public class User implements Serializable {@TableId(type = IdType.AUTO)private Integer id;@TableField(value = "name")private String name;@TableField(value = "age")private Integer age;@TableField(value = "state")private String state;@TableField(exist = false)private static final long serialVersionUID = 1L;@TableField(value = "count(*)",insertStrategy = FieldStrategy.NEVER,updateStrategy = FieldStrategy.NEVER)private  Integer count;//这个地方@TableField(value = "sum(age)",insertStrategy = FieldStrategy.NEVER,updateStrategy = FieldStrategy.NEVER)private  Integer ages;
}

第二步：查询接口中修改

   @GetMapping("/count")public List<User> count(){new QueryWrapper<>()LambdaQueryWrapper<User> queryWrapper = new LambdaQueryWrapper<>();//这个地方新增了一个字段queryWrapper.select(User::getState,User::getCount,User::getAges);queryWrapper.groupBy(User::getState);List<User> list = userService.list(queryWrapper);return list;}

返回的结果

[{"id": null,"name": null,"age": null,"state": "1","count": 3,"ages": 6},{"id": null,"name": null,"age": null,"state": "2","count": 2,"ages": 9}
]

🍚总结

大功告成，撒花致谢🎆🎇🌟，关注我不迷路，带你起飞带你富。
Writted By 知识浅谈