2.1

import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;
import com.example.elderlyassessmentsystem.entity.Elderly;
import com.example.elderlyassessmentsystem.mapper.ElderlyMapper;

import java.util.List;

@Service
public class ElderlyService extends ServiceImpl<ElderlyMapper, Elderly> {
public void saveElderly(Elderly elderly) {
save(elderly);
}

public List<Elderly> listElderly() {
    return list();
}

public List<Assessment> listAssessmentsByElderlyId(Long elderlyId) {
    QueryWrapper<Assessment> wrapper = new QueryWrapper<>();
    wrapper.eq("elderly_id", elderlyId);
    return new AssessmentMapper().selectList(wrapper);
}

}
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import org.springframework.stereotype.Service;
import com.example.elderlyassessmentsystem.entity.Assessment;
import com.example.elderlyassessmentsystem.mapper.AssessmentMapper;

import java.util.List;

@Service
public class AssessmentService extends ServiceImpl<AssessmentMapper, Assessment> {
public void saveAssessment(Assessment assessment) {
save(assessment);
}

public List<Assessment> listAssessmentsByConditions(QueryWrapper<Assessment> wrapper) {
    return list(wrapper);
}

public Double calculateAverageScore() {
    QueryWrapper<Assessment> wrapper = new QueryWrapper<>();
    wrapper.select("AVG(ability_score)");
    return new AssessmentMapper().selectObjs(wrapper).stream().findFirst().map(Double::valueOf).orElse(0.0);
}

}