设有学生表student(学号sno, 姓名sname, 年龄 sage，系别dept)、课程表Course(课程号cno，课程名称cname)和选课表sc（学号sno，课程号cno，成绩grade），用Oracle PL/SQL语言设计一个名为pkg_student程序包，要求：

（1）写出程序包头和包体的定义，其中包含函数avgGradePerCourse和存储过程printAvgGradeCourse。

（2）函数avgGradePerCourse计算某门课程的平均成绩，必须用PL/SQL表（索引表）实现。

（3）存储过程printAvgGradeCourse打印输出某个系每门课程的平均成绩，必须使用游标。

（4）调用pkg_student程序包中相应的函数或存储过程-Have student table student (Student ID sno, name sname, age, sage, University Department dept), curriculum Course (course number cno, course name cname) and enrollment form sc (Student ID sno, course number cno, performance grade), using Oracle PL/SQL language to design a package called pkg_student require: (1) Write program header and the definition of inclusion, which contains functions and stored procedures avgGradePerCourse printAvgGradeCourse. (2) function avgGradePerCourse calculate a course grade point average, must be PL/SQL table (index table) implementation. (3) print out a stored procedure printAvgGradeCourse Department of average scores for each course, you must use cursors. (4) call pkg_student package corresponding function or stored procedure