假设有如下的关系R和S：若关系R和S的关系代数操作的结果如下，这是执行了 A: R×S B: R×S C: R×S D: R×SC＜EC＞E E: B＝ F: B

公告：维护QQ群：833371870，欢迎加入！
公告：维护QQ群：833371870，欢迎加入！
公告：维护QQ群：833371870，欢迎加入！

2022-07-28 问题

假设有如下的关系R和S：若关系R和S的关系代数操作的结果如下，这是执行了 A: R×S B: R×S C: R×S D: R×SC＜EC＞E E: B＝ F: B

2022-10-26 问题

检索选修课程号为“D3”的学生中成绩最高的学生的学号，正确的、SELECT语句是______ A: SELECT S# B: FROM SC C: WHERE C#='D3'AND GRADE＞= D: (SELECT GRADE FROM SC E: WHERE C#='D3')； F: SELECT S# G: FROM SC H: WHERE C#='D3'AND GRADE IN I: (SELECT GRADE FROM SC J: WHERE C#='D3')； K: SELECT S# L: FROM SC M: WHERE C#='D3'AND GRADE NOT IN N: (SELECT GRADE FROM SC O: WHERE C#='D3')； P: SELECT S# Q: FROM SC R: WHERE C#='D3'AND GRADE＞=ALL S: (SELECT GRADE FROM SC T: WHERE C#='D3')；

检索选修课程号为“D3”的学生中成绩最高的学生的学号，正确的、SELECT语句是______ A: SELECT S# B: FROM SC C: WHERE C#='D3'AND GRADE＞= D: (SELECT GRADE FROM SC E: WHERE C#='D3')； F: SELECT S# G: FROM SC H: WHERE C#='D3'AND GRADE IN I: (SELECT GRADE FROM SC J: WHERE C#='D3')； K: SELECT S# L: FROM SC M: WHERE C#='D3'AND GRADE NOT IN N: (SELECT GRADE FROM SC O: WHERE C#='D3')； P: SELECT S# Q: FROM SC R: WHERE C#='D3'AND GRADE＞=ALL S: (SELECT GRADE FROM SC T: WHERE C#='D3')；

2022-06-19 问题

假定： A: S B: C，SC C: S，SC D: S，C，SC

2022-06-18 问题

LC和SC分别具有几个工作站系统（） A: LC:3,SC:3 B: LC:4,SC:2 C: LC:2,SC:4 D: LC:4,SC:3

2022-06-17 问题

有关系表SC(S# , C#, Score),求“001”号课成绩比“002”号课成绩高的所有学生的学号。下列SQL语句正确的是_________。[br][/br](单选题) A: Select S1.S B: From SC S1, SC S2 Where S1.S C: = S2.S D: and S1.C E: =‘001’ and S2.C F: =‘002 ; G: Select S1.S H: From SC S1, SC S2 Where S1.S I: = S2.S J: and S1.C K: =‘001’ and S2.C L: =‘002’ and S1.Score > S2.Score; M: Select S1.S N: From SC S1, SC S2 Where S1.S O: = S2.S P: and S1.C Q: =‘001’ and S2.C R: =‘002’ and S2.Score > S1.Score; S: Select * From SC S1, SC S2 Where S1.S T: = S2.S U: and S1.C V: =‘001’ and S2.C W: =‘002’ and S1.Score > S2.Score;

有关系表SC(S# , C#, Score),求“001”号课成绩比“002”号课成绩高的所有学生的学号。下列SQL语句正确的是_________。[br][/br](单选题) A: Select S1.S B: From SC S1, SC S2 Where S1.S C: = S2.S D: and S1.C E: =‘001’ and S2.C F: =‘002 ; G: Select S1.S H: From SC S1, SC S2 Where S1.S I: = S2.S J: and S1.C K: =‘001’ and S2.C L: =‘002’ and S1.Score > S2.Score; M: Select S1.S N: From SC S1, SC S2 Where S1.S O: = S2.S P: and S1.C Q: =‘001’ and S2.C R: =‘002’ and S2.Score > S1.Score; S: Select * From SC S1, SC S2 Where S1.S T: = S2.S U: and S1.C V: =‘001’ and S2.C W: =‘002’ and S1.Score > S2.Score;

2022-06-10 问题

在CAD中缩放（SC）固定尺寸应执行的操作是？ A: 比例 B: 比例因子 C: 参照（R） D: 复制（C）

2022-06-04 问题

考虑到参照完整性的外码设计，如图所示的student,course,sc三张表的创建顺序应为（）。 A: sc,course,student B: sc,student,course C: student,sc,course D: student,course,sc

2022-06-16 问题