Public relations practice is the deliberat e, planned and sustained effort to establish and maintain mutual understanding between an organization and its public.
【简答题】设教学数据库中有三个基本表:学生表S(SNO,SNAME,AGE,),其属性分别表示学号、学生姓名、年龄、性别。课程表C(CNO,CNAME,TEACHER),其属性分别表示课程号、课程名、上课教师名。选课表SC(SNO,CNO,GRADE),其属性分别表示学号、课程号、成绩。 有如下SQL查询语句: select CNO from C where CNO not in (select CN...