在ORACLE中，语句 select “test”||null

A.WHERECURRENTOF

B.INTO

C.FORUPDATE

D.ORDERBY

“从学生选课信息表中找出无成绩的元组”的SQL语句是（ ）。 A．SELECT*FROM sc WHERE grade＝NULL B．SELECT*FROM sc WHERE grade IS＇＇ C．SELECT*FROM sc WHERE grade IS NULL D．SELECT*FROM sc WHERE grade＝＇＇

下列语句错误的是( )

A.select * from orders where ordername is not null;

B.select * from orders where ordername<>null;

C.select * from orders where ordername is null;

D.select * from orders where ordername not is null;

A.SELECT name FROM V$CONTROLFILE

B.SELECT name FROM V$CTRLLFILE

C.SELECT name FROM V$USERFILES

D.SELECT name FROM V$DBAFILE

A.select ename,nvl（comm.,0）from emp

B.select ename,null（comm.,0）from emp

C.SELECT ename,NULLIF（comm,0）FROM emp

D.SELECT ename,DECODE（comm.,NULL,0）FROM emp

A.SELECTnameFROMteacherWHEREemail=NULL;

B.SELECTnameFROMteacherWHEREemail<>NULL;

C.SELECTnameFROMteacherWHEREemailISNULL;

D.SELECTnameFROMteacherWHEREemailISNOTNULL;

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,

CONSTRAINT PK_Customers PRIMARY KEY(CustomerID)

)

大部分的国家或地区只包含2-3个客户，而一些国家包括多于20个客户。现在公司想对客户数量在10(含10)个以上的国家进行广告宣传，你使用( )语句将这些国家列出。

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

若在教师表中查找还没有输入工龄的记录,使用的SQL语句为

A．SELECT * FROM 教师 WHERE 工龄IS NOT NULL

B．SELECT * FROM 教师 WHERE 工龄=0

C．SELECT * FROM 教师 WHERE 工龄 IS NULL

D．SELECT * FROM 教师 WHERE 工龄=NULL

A.ALTER USER test IDENTIFIED BY oracle

B.ALTER USER test PASSWORD oracle

C.CREATE USER test IDENTIFIED BY oracle

D.UPDATE USER test IDENTIFIED BY oracle

A.ORDER BY

B.FROM

C.GROUP BY

D.JOIN