MyBatis-Plus LambdaQueryWrapper 分组统计 - 代码示例

要在MyBatis-Plus中使用LambdaQueryWrapper进行分组统计，您可以使用以下代码实现：

import com.baomidou.mybatisplus.core.conditions.query.LambdaQueryWrapper;
import com.baomidou.mybatisplus.core.mapper.BaseMapper;
import com.baomidou.mybatisplus.core.metadata.IPage;
import com.baomidou.mybatisplus.extension.plugins.pagination.Page;
import com.baomidou.mybatisplus.extension.service.IService;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;

import java.util.List;
import java.util.Map;

@Service
public class YourService extends ServiceImpl<YourMapper, YourEntity> implements IService<YourEntity> {

    public List<Map<String, Object>> groupAndCount() {
        LambdaQueryWrapper<YourEntity> queryWrapper = new LambdaQueryWrapper<>();
        queryWrapper.select(YourEntity::getGroupColumn, 'count(1) as count')
                .groupBy(YourEntity::getGroupColumn);
        return baseMapper.selectMaps(queryWrapper);
    }

    public IPage<Map<String, Object>> groupAndCountWithPage(int current, int size) {
        IPage<YourEntity> page = new Page<>(current, size);
        LambdaQueryWrapper<YourEntity> queryWrapper = new LambdaQueryWrapper<>();
        queryWrapper.select(YourEntity::getGroupColumn, 'count(1) as count')
                .groupBy(YourEntity::getGroupColumn);
        return baseMapper.selectMapsPage(page, queryWrapper);
    }
}

在上述代码中，YourEntity是您的实体类，YourMapper是您的Mapper接口，YourService是您的Service类。groupAndCount方法使用LambdaQueryWrapper进行分组统计，返回一个List<Map<String, Object>>，其中每个Map代表一条统计结果。groupAndCountWithPage方法使用LambdaQueryWrapper进行分组统计，并支持分页查询，返回一个IPage<Map<String, Object>>。

请根据您的实际情况修改代码中的实体类、Mapper接口和Service类的名称，并确保您已正确配置了MyBatis-Plus的依赖和配置文件。