下列函数返回类型为数值型的是( )。

A．SELECT COUNT(*)FROM教师表INNER JOIN学院表ON教师表，系号=学院表，系号WHERE系名=“计算机”
B．SELECT COUNT(*)FROM教师表INNER JOIN学院表ON教师表，系号=学院表，系号0RDER BY教师表系号HAVING学院表，系名=“计算机”
C．SELECT SUM(*)FROM教师表INNER JOIN学院表ON教师表，系号=学院表，系号GROUP BY教师表，系号
D．SELECT SUM(*)FROM教师表INNER JOIN学院表ON教师表，系号=学院表，系号0RDER BY教师表，系号HAVING学院表，系名=“计算机”

A．CREATE CLASS mylib OF student AS Pcrson
B．CREATE CLASS student OF Person AS mylib
C．CREATE CLASS student OF mylib AS Person
D．CREATE CLASS Person OF mylib AS student