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✅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
代码语言：javascript
复制
@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
代码语言：javascript
复制
@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
代码语言：javascript
复制
[
{
"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
代码语言：javascript
复制
@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
代码语言：javascript
复制
@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
代码语言：javascript
复制
[
{
"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
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