数据库SQL综合分析题
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数据库SQL综合分析题
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1.?(簡答題, 40分)
假設學生-課程數據庫關系模式如下所示:
Student(S#,Sname,Sage,Ssex)表示學生關系,屬性為學號、姓名、年齡、性別;
Course(C#,Cname,Ccredit)表示課程關系,屬性為課程號、課程名,學分;
SC(S#,C#,Score)表示選修關系,屬性為學號、課程號、考試成績;
各表中數據見下面表格所示,請說明:
(1)下面SQL語句的功能。
(2)執行過程。
(3)查詢結果。
本題滿分40分,其中SQL語句功能10分;語句的執行過程20分,請從SQL語句各子句的執行次序角度分析該語句的執行過程;查詢結果10分,可用表格形式給出。
SELECT? Student.S#,Sname,Sage,SUM(Ccredit) SumCredit
FROM Student,SC,Course
WHERE Student.S#=SC.S# AND Course.C#=SC.C# AND Ssex='女' AND Score>=60
GROUP BY Student.S#,Sname,Sage Having Count(*)>2
ORDER BY SumCredit DESC,Sname ASC;
create table Student( S# char(5) primary key, Sname char(20), Sage number, Ssex char(2) ); create table Course( C# char(5)primary key, Cname char(20), Ccredit char(5) ); create table SC( S# char(5), C# char(5), Score number, primary key(S#,C#), foreign key(S#) references Student(S#), foreign key(C#) references Course(C#) ); insert into Student values('101','李紅梅',20,'女'); insert into Student values('102','李琳琳',19,'女'); insert into Student values('103','張強',20,'男'); insert into Student values('104','譚莉',21,'女'); insert into Student values('105','趙茂盛',18,'男'); insert into Student values('106','李曉光',19,'男'); insert into Student values('107','何虹',20,'女'); insert into Student values('108','王美麗',21,'女'); insert into Student values('109','吳嫦娥',29,'女'); insert into COURSE values('1','高級語言程序設計','3'); insert into COURSE values('2','大學英語1','3'); insert into COURSE values('3','數據結構','3.5'); insert into COURSE values('4','操作系統原理','3'); insert into COURSE values('5','Python程序設計','2'); insert into COURSE values('6','高等數學','4.5'); insert into SC values ('101','1',80); insert into SC values ('101','2',75); insert into SC values ('101','3',90); insert into SC values ('101','4',87); insert into SC values ('102','1',85); insert into SC values ('102','3',75); insert into SC values ('102','6',90); insert into SC values ('103','1',70); insert into SC values ('103','2',65); insert into SC values ('103','3',85); insert into SC values ('104','2',75); insert into SC values ('104','3',88); insert into SC values ('104','4',77); insert into SC values ('105','1',90); insert into SC values ('105','2',87); insert into SC values ('106','1',72); insert into SC values ('107','2',76); insert into SC values ('108','1',75); insert into SC values ('108','2',55); insert into SC values ('108','3',70); insert into SC values ('109','1',75); insert into SC values ('109','3',75); insert into SC values ('109','5',75); SELECT Student.S#,Sname,Sage,SUM(Ccredit) SumCreditFROM Student,SC,CourseWHERE Student.S#=SC.S# AND Course.C#=SC.C# AND Ssex='女' AND Score>=60GROUP BY Student.S#,Sname,Sage Having Count(*)>2ORDER BY SumCredit DESC,Sname ASC;總結
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