关联集合对象

1.Teacher.java

private List list；//添加list，查找老师的所有学生

2.TeacherMapper.xml

select * from teacher

3.StudentMapper.xml

select * from student where tid=#{0}

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使用实现加载集合数据（联合查询方式）

1.在TeacherMapper.xml中配置

//List list

select t.id tid,t.name tname,s.id sid.s.name sname,age,tid from teacher t LEFT JOIN student s on t.id=s.id