《数据库应用技术》吉大22年12月考前模拟辅导100分答案非答案

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答案来源：www.ybaotk.com《数据库应用技术》考前练兵


1.[单选题] Given the tables:

COUNTRY STAFF

id name person cities id name

1 Argentina 1 10 1 Aaron

2 Canada 2 20 2 Adams

3 Cuba 2 10 3 Jones

4 Germany 1 0

5 France 3 5

6 Italy 1 5

the report:

id name number_of_countries

---------- ---------- -------------------

1 Aaron 3

and the SQL statement:

SELECT B.id,B.name,COUNT(DISTINCT A.name) AS number_of_countries

FROM country A, staff B

WHERE B.id=A.person

GROUP BY B.id,B.name

HAVING COUNT(DISTINCT A.name)>:count_var

Which of the following values does :count_var require to print out the above

report?


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说明


    A.1


    B.2


    C.3


    D.4


    答:——B——


2.[单选题] Given the EMPLOYEE table definition:

CREATE TABLE employee (

workdept CHAR(30),

salary INTEGER

)

Which of the following is a correct usage of parameter markers in a JDBC

program?


    A.String sql =

"UPDATE employee SET salary=salary*?WHERE workdept=?";

statement stmt=con.createStatement(sql);


    B.String sql =

"UPDATE employee SET salary=salary*?WHERE workdept=?";

statement stmt=con.createStatement(sql);


    C.String sql =

"UPDATE employee SET salary=salary*?WHERE workdept=?";

statement stmt=con.createStatement(sql);


    D.String sql =

"UPDATE employee SET salary=salary*?WHERE workdept=?";

statement stmt=con.createStatement(sql);


    答:——C——


3.[单选题] 给定三个表：学生表S，课程表C和学生选课表SC，它们的结构分别如下：

S（S

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，SN，SEX，AGE，DEPT）

C（C

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，CN）

SC（S

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，C

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，GRADE）

其中：S

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为学号，SN为姓名，SEX为性别，AGE为年龄，DEPT为系别，C

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为课程 号，CN为课程名，GRADE为成绩。

对表SC建立如下视图：

CREATE VIEW S_GRADE(S

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,C_NUM,AVG_GRADE)

AS SELECT S

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,COUNT(C

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),AVG(GRADE)

  FROM SC

  GROUP BY S