【单选题】公司有一个客户的数据表,此表的建立语句如下: CREATE TABLE Customers (CustomerID int NOT NULL, CustomerName varchar(50) NOT NULL, ContactName varchar(30) NULL, Phone varchar(20) NULL, Country varchar(30) NOT NULL, CONSTRAIN...
A.
SELECT Country FROM Customers GROUP BY Country HAVING COUNT (Country)>=10
B.
SELECT TOP 10 Country FROM Customers
C.
SELECT TOP 10 Country FROM Customers FROM (SELECT DISTINCT Country FROM Customers) AS X GROUP BY Country HAVING COUNT(*)>= 10
D.
SET ROWCOUNT 10 SELECT Country, COUNT (*) as “NumCountries” FROM Customers GROUP BY Country ORDER BY NumCountries, Desc
【单选题】已知关系模式:图书(图书编号,图书类型,图书名称,作者,出版社,出版日期,ISBN),图书编号唯一识别一本图书。建立“计算机”类图书的视图Computer-BOOK,并要求进行修改、插入操作时保证该视图只有计算机类的图书。实现上述要求的SQL语句如下: CREATE (56)。 AS SELECT图书编号,图书名称,作者,出版社,出版日期 FROM图书 WHERE图书类型='计算机' with c...