answer_3.htm

软件设计师模拟试卷,点击里面的Exe文件可以随机出题

lang=EN-US style='mso-bidi-font-size:10.5pt'>3</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>）数据的分布独立性；</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>4</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>）场地的自治和协调；</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>5</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>）数据的冗余及冗余透明性。<span
lang=EN-US><o:p></o:p></span></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>虽然上述银行的数据库系统具有性质</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>1</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>、</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>3</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>以及</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>4</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>和</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>5</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>的一部分，但关键是没有数据的逻辑整体性和不同场地之间的协调性等，这恰恰是分布式数据库系统的关键所在。因此，上述银行数据库系统算不上分布式数据库系统。<span
lang=EN-US><o:p></o:p></span></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>【解析】本题中的</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>E-R</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>图中有</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>4</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个实体集、</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>2</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个多对多联系和</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>2</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个一对多联系，根据上述</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>E-R</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>图转换关系模型的规则可以转换成</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>6</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个关系。<span
lang=EN-US><o:p></o:p></span></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>4</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个实体集转换的</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>4</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个关系</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>(Customer</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>、</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Account</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>、</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Branch</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>和</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Loan)</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，对于一对多联系</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>B</span><span lang=EN-US
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>-</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>L</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>和</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>B-A</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>则是将<span
lang=EN-US>&quot;一&quot;端</span></span><span lang=EN-US style='mso-bidi-font-size:
10.5pt'>(</span><span style='mso-bidi-font-size:10.5pt;font-family:宋体;
mso-hansi-font-family:"Times New Roman"'>关系</span><span lang=EN-US
style='mso-bidi-font-size:10.5pt'>Branch)</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>的码</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Bname</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>加入到<span
lang=EN-US>&quot;多&quot;端所转换的关系</span></span><span lang=EN-US style='mso-bidi-font-size:
10.5pt'>(Account</span><span style='mso-bidi-font-size:10.5pt;font-family:宋体;
mso-hansi-font-family:"Times New Roman"'>和</span><span lang=EN-US
style='mso-bidi-font-size:10.5pt'>Loan)</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>。此</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>4</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个关系分别为：<span
lang=EN-US><o:p></o:p></span></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Customer(<u>idno</u></span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>name</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>address</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>phone)<o:p></o:p></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Account(<u>Ano</u></span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>balance</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Bname)<o:p></o:p></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Branch(<u>Bname</u></span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>city</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>assets)<o:p></o:p></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Loan(<u>Lno</u></span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Bname</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>amount)<o:p></o:p></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>4</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个关系中，</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Account</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>和</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Loan</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>的属性</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Bname</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>均参照</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Branch</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>的码</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Bname</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，为外码。<span
lang=EN-US><o:p></o:p></span></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>2</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个多对多联系转换为</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>2</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个关系，两端的码及联系的属性为关系的属性，两端的码共同组合为该关系的码。此</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>2</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个关系分别为：<span
lang=EN-US><o:p></o:p></span></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Deposit(<u>idno</u></span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，</span><u><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Ano</span></u><span lang=EN-US
style='mso-bidi-font-size:10.5pt'>)<o:p></o:p></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Borrow(<u>idno</u></span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>，</span><u><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Lno</span></u><span lang=EN-US
style='mso-bidi-font-size:10.5pt'>)<o:p></o:p></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>其中的</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>idno</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>、</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Ano</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>和</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Lno</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>分别参照</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Customer</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>的</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>idno</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>、</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Account</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>的</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Ano</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>和</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Loan</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>的</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Lno</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>。<span
lang=EN-US><o:p></o:p></span></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>问题</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>2</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>中是要查询在该银行中一笔贷款贷给多个</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>(</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>至少</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>2</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>个</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>)</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>客户的所有贷款号和发放贷款的支行名称。</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Borrow</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>表中记录着各贷款号和该贷款的客户，</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Loan</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>表中记录着各贷款号和发放该贷款的支行，要完成题目查询必须将</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Borrow</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>和</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Loan</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>联系起来，即需要两者的贷款号相等。所以填空</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>(1)</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>应该为</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>Borrow.Lno=Loan.Lno</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>。<span
lang=EN-US><o:p></o:p></span></span></p>

<p class=MsoNormal style='mso-layout-grid-align:none;text-autospace:none'><span
lang=EN-US style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:
"Times New Roman"'>&quot;一笔贷款贷给多个客户&quot;则需要按贷款号进行分组，只有客户个数至少两个的组才是满足查询要求的分组。对于分组的条件应该添加在</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>HAVING</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>子句中，个数的统计需利用</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>COUNT(idno)</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>函数，因此填空</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>(2)</span><span style='mso-bidi-font-size:
10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>为</span><span
lang=EN-US style='mso-bidi-font-size:10.5pt'>COUNT(idno)&gt;=2</span><span
style='mso-bidi-font-size:10.5pt;font-family:宋体;mso-hansi-font-family:"Times New Roman"'>。<span
lang=EN-US><o:p></o:p></span></span></p>

<p class=MsoNormal align=left style='text-align:left;mso-layout-grid-align:
none;text-autospace:none'><span style='mso-bidi-font-size:10.5pt;font-family:
宋体;mso-hansi-font-family:"Times New Roman"'>问题</span><span lang=EN-US
style='mso-bidi-font-size:10.5pt'>3</span><span style='mso-bidi-font-size:10.5pt;
font-family:宋体;mso-hansi-font-family:"Times New Roman"'>主要考查分布式数据库系统的必备条件。</span><span
style='font-size:8.5pt;font-family:"MS Sans Serif";mso-font-kerning:0pt;
mso-ansi-language:ZH-CN'><o:p></o:p></span></p>

<p class=MsoNormal><span lang=EN-US><![if !supportEmptyParas]>&nbsp;<![endif]><o:p></o:p></span></p>

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