【单选题】
假设同一名称的产品有不同的型号和产地,则计算每种产品平均单价的SQL命令为
①
A. SELECT 产品名称,AVG(单价) FROM 产品 GROUP BY 单价
②
SELECT 产品名称,AVG (单价) FROM 产品 GROUP BY 产品单价
③
SELECT 产品名称,AVG (单价) FROM 产品 ORDER BY 产品单价
④
SELECT 产品名称,AVG (单价) FROM 产品 ORDER BY 单价
【单选题】
Do you mind telling me where you’re from?
①
Certainly. I’m from London
②
Sure. I was born in London
③
Not really, you can do it
④
Certainly not. I’m from London
【单选题】
有关系S(SNO, SNAME, SAGE),C(CNO, CNAME),SC(SNO, CNO, GRADE)。其中SNO是学生号,SNAME是学生姓名,SAGE是学生年龄, C#是课程号,CNAME是课程名称。要查询选修“ACCESS”课的年龄不小于20的学生姓名,则SQL语句是: SELECTSNAME FROM S,C,SC WHERE子句。 这里的WHERE子句的内容是( )。
①
S.SNO = SC.SNO and C.CNO = SC.CNO and SAGE>=20 and CNAME=‘ACCESS’
②
S.SNO = SC.SNO and C.CNO = SC.CNO and SAGE >=20 and CNAME in ‘ACCESS’
③
SAGE in>=20 and CNAME in ‘ACCESS’
④
SAGE>=20 and CNAME=’ ACCESS’