《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
答案来源：www.yabaojy.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 ，SN，SEX，AGE，DEPT）
C（C ，CN）
SC（S ，C ，GRADE）
其中：S 为学号，SN为姓名，SEX为性别，AGE为年龄，DEPT为系别，C 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 ,C_NUM,AVG_GRADE)
AS SELECT S ,COUNT(C ),AVG(GRADE)
FROM SC
GROUP BY S
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