student( sid, name, age, gender, department)
course(cno, name, credit, teacher)
register( sid, cno, semester)
用关系代数 写出下面查询。
a. Find the names of students from “qq” department who registered a course taught by “bb”
找出所有来自qq系并注册了一个bb教授的课程 的学生。
b. Find the names of students who registered all courses taught by “bb”
找出这样的学生：注册所有bb教的课程
------解决方案--------------------
关系代码的符号打不出来，
PI s.depart='qq' & teacher='bb' (student X course X register)
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