刚学数据库,遇到一道关于数据库sql语句的题目,实在不会,请高手帮忙解答...答:Create View DeptPro AS select Pnumber, Dnumber, Dname, sum(Hours) Hours from (select A.Pnumber, A.Hours, C.Dnumber, C.Dname from WORKS_ON A Inner join EMPLOYEE B on A.ESSN=B.ESSN Inner join DEPARTMENT C on B.Dnumber=C.Dnumber ) Tbl group by Pnumber,Dnumber,Dname --...