已知表:SC(S#,C#,CRADE),其中S#、C#、CRADE分别代表学号、选修课号、成绩。则统计选修了课程的学生的总数的SQL语句应为:
A: SELECT COUNT(DISTINCT S
B: ) FROM SC
C: SELECT COUNT(DISTINCT *) FROM SC
D: SELECT COUNT(S
E: ) FROM SC
F: SELECT COUNT(DISTINCT C
G: ) FROM SC
A: SELECT COUNT(DISTINCT S
B: ) FROM SC
C: SELECT COUNT(DISTINCT *) FROM SC
D: SELECT COUNT(S
E: ) FROM SC
F: SELECT COUNT(DISTINCT C
G: ) FROM SC
举一反三
- 查询选修了课程的学生人数,SQL语句为SELECT COUNT(DISTINCT S#) FROM SC
- 以下SQL语句中,____________可以在“学生-课程”数据库正确实现“查询选修了课程的学生总人数”。 A: SELECT COUNT(Sno)FROM SC B: SELECT COUNT(DISTINCT Sno)FROM SC C: SELECT COUNT(*)FROM SC D: SELECT SUM(Sno)FROM SC
- 设有关系S(S#,SNAME,AGE,SEX)、C(C#,CNAME,TEACHER)和SC(S#,C#,GRADE),请将实现以下功能的SQL语句填写完整:[br][/br] (4)检索全部学生都选修的课程的课程号(C#)和课程名(CNAME)。 [br][/br] 方法1: SELECT C#,CNAME FROM C WHERE (SELECT * FROM S WHERE (SELECT * FROM SC WHERE C.C#=SC.C# AND S.S#=SC.S#)) 方法2: select c#,cname from c where c# in( select c# from sc group by having count(distinct s#)=(select count(*) from ))
- 以下哪条语句可以实现查询选了课的学生人数( )。 A: select count(*) from sc B: select count(sno) from sc C: select count(distinct sno) from sc D: select count(cno) from sc
- 查询选修了课程号为C2的学生号和姓名,用下列SQL的SELECT语句表达时,哪一个是错误的( ) A: SELECT S.S#,SNAME FROM S WHERE S.S# B: =(SELECT SC) S# FROM SC WHERE C#=‘C2’) C: SELECT S.S#,SNAME FROMS,SC D: WHERE S.S# S E: S# AND C#=‘C2’C) SELECT S. S#,SNAME FROM S,SC F: WHERE S.S# SC) S# AND C#=‘C2’ORDER BY S.S# G: SELECT S.S#,SNAME FROM S