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【单选题】
假设有关系R(A,B,C),其主码为A;关系S(D,A),其主码为D,外码为A。 如下图所示: 则关系S中违反完整性规则的是( )。A.
<3,3>
B.
<4,1>
C.
<1,2>
D.
<2,null>
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举一反三
【单选题】You have created a resource plan， DAY. You execute the following code： SQL> BEGIN DBMS_RESOURCE_MANAGER.CREATE_SIMPLE_DIRECTIVE （ PLAN => ’DAY’， COMMENT => ’DEPARTMENTS PLAN’， ...
A.
The DEVELOPERS and DEPARTMENTS subplans will be allocated CPU equally.
B.
The DEVELOPERS subplan will be allocated 100 percent CPU if there are no resources allocated to the DEPARTMENTS subplan.
C.
The DEPARTMENT subplan will be allocated 100 percent CPU if there are no resources allocated to the DEVELOPERS subplan.
D.
The second code will not execute because one resource plan cannot be used by more than one subplan.
【单选题】In the use of closeness ratings for process layouts, the code "U" means the closeness between two departments is:
A.
(U)nknown
B.
(U)nusually important
C.
of (U)sual importance
D.
(U)nimportant
E.
(U)ndesirable
【单选题】关系模式department(code,name)、employee(code,name,sex,dept,phone),查询“研发部”的员工信息,查询结果包括code,name,sex,phone,正确的语句是()
A.
select code,name,sex,phone from employee where dept =’研发部’;
B.
select code,name,sex,phone from employee em,department de where de.code=em.dept and de.dept=’研发部’;
C.
select code,name,sex,phone from employee em,department de where de.code=em.code and de.name=’研发部’;
D.
Select em.code,name,sex,phone from employee em,department de where de.code=em.dept and de.name=’研发部’;
【单选题】关系模式department(code,name)、employee(code,name,sex,dept,phone),查询每个部门的员工数量,查询结果包括code,name,emps,正确的语句是()
A.
select code, name,emps from department de left join (select dept,count(*) emps from employee group by dept) vem on de.code=vem.dept;
B.
select code, name ,count(*) emps from department de,employee group by dept on de.code=em.dept;
C.
select code, name, count(*) emps from department de,employee group by dept where de.code=em.dept;
D.
select code, name, count(*) emps from department de,employee on de.code=em.dept group by dept;
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