S-L(Sno,Sdept,Sloc)属于三范式（B）
注：Sno →Sdept，Sdept→Sloc
注：Sno →Sdept，Sdept→Sloc
举一反三
- 关系模式SLC(sno, sdept, sloc, cno, grade)中存在的依赖有（）
- S_T数据库关系图如下:[img=332x128]17e448fc85e997f.jpg[/img]查询与“刘晨”在同一个系学习的学生,要求显示学生学号(Sno)、姓名(Sname)及系别(Sdept)。下列SQL语句正确的是()。 A: SELECT Sno, Sname, Sdept FROM Student WHERE Sdept = (SELECT Sdept FROM Student WHERE Sname = '刘晨'); B: SELECT S1.Sno, S1.Sname , S1.Sdept FROM Student S1 , Student S2 WHERE S1.Sdept = S2.Sdept AND S2.Sname = '刘晨'; C: SELECT Sno, Sname, Sdept FROM Student WHERE Sdept IN (SELECT Sdept FROM Student WHERE Sname = '刘晨'); D: SELECT Sno, Sname, Sdept FROM Student WHERE Sdept LIKE (SELECT Sdept FROM Student WHERE Sname = '刘晨');
- 一个描述学校的数据库模式S (SNO，SDEPT，MN，CNAME，G)。SNO是学号，SDEPT是系名，MN表示系主任，CNAME是课名，G是成绩
- 设学生关系S(SNO,SNAME,SSEX,SAGE,SDEPT)的主键为SNO,学生选课关系SC(SNO,CNO,SCORE)的主键为SNO和CNO,关系R(SNO,CNO,SSEX,SAGE,SDEPT,SCORE)的主键为SNO和CNO,关系R满足() A: 1NF B: 2NF C: 3NF D: 都不对
- 【单选题】针对学生表student（sno,sname,ssex,sage,sdept），其中sno为学号，sname为姓名，ssex为性别，sage为年龄，sdept为系别。查询学生的姓名sname，系别sdept和年龄sage，显示时按系别升序排列，系别相同的再按年龄降序排列。() A. select * from student order by sdept , sage B. select sname, sdept, sage from student order by sdept , sage desc C. select sname, sdept, sage from student order by sdept desc , sage D. select * from student order by sdept desc, sage