给定教师关系Teacher(T_no,T_name,Dept name,Tel),其中属性T_no、T_name、Dept_name和Tel的含义分别为教师号、教师姓名、学院名和电话。用SQL创建一个“给定学院名求该学院的教师数”的函数如下:Create function Dept_count(Dept_name varchar(20))(请作答此空)begain( )select count(*)into d_count from Teacher where Teacher.Dept_name=Dept_name return d_count end
Areturns integer
Breturns d_count integer
Cdeclare integer
Ddeclare d_count integer