student-management/src/main/java/cn/zyp/stusystem/service/impl/ClassServiceImpl.java

package cn.zyp.stusystem.service.impl;


import cn.zyp.stusystem.entity.GradeClass;
import cn.zyp.stusystem.entity.Student;
import cn.zyp.stusystem.mapper.ClassMapper;
import cn.zyp.stusystem.mapper.StudentMapper;
import cn.zyp.stusystem.service.ClassService;
import com.baomidou.mybatisplus.annotation.IdType;
import com.baomidou.mybatisplus.annotation.TableField;
import com.baomidou.mybatisplus.annotation.TableId;
import com.baomidou.mybatisplus.annotation.TableName;
import com.baomidou.mybatisplus.core.conditions.query.QueryWrapper;
import com.baomidou.mybatisplus.extension.service.impl.ServiceImpl;
import lombok.ConfigurationKeys;
import lombok.Data;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;


@Service
public class ClassServiceImpl extends ServiceImpl<ClassMapper, GradeClass> implements ClassService {

    @Autowired
    private StudentMapper studentMapper;

    @Override
    public List<GradeClass> findClassByGradeId(Integer gradeId) {
        QueryWrapper<GradeClass> queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("grade",gradeId);
        return baseMapper.selectList(queryWrapper);
    }

    @Override
    public boolean isClassHasStudent(Integer classId) {
        QueryWrapper<Student> queryWrapper = new QueryWrapper<>();
        queryWrapper.eq("class_id",classId);

        return studentMapper.selectCount(queryWrapper)>0;
    }
}