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<div id="pf1" class="pf w0 h0" data-page-no="1"><div class="pc pc1 w0 h0"><img class="bi x0 y0 w1 h1" alt="" src="https://static.pudn.com/prod/directory_preview_static/622b3c6c81ded46b7f9417de/bg1.jpg"><div class="c x0 y1 w2 h2"><div class="t m0 x1 h3 y2 ff1 fs0 fc0 sc0 ls0 ws0">一个数据库设计的例子</div><div class="t m0 x2 h4 y3 ff1 fs1 fc0 sc0 ls0 ws0">题目:<span class="sc1">为学校设计一个课程选修的管理系统。</span></div><div class="t m0 x2 h4 y4 ff1 fs1 fc0 sc0 ls0 ws0">一、需求说明</div><div class="t m0 x3 h4 y5 ff1 fs1 fc0 sc1 ls0 ws0">教师向所在学院提出开设选修课的申请,并在申请中明确课程名称、所需学时和教材,</div><div class="t m0 x2 h4 y6 ff1 fs1 fc0 sc1 ls0 ws0">学院<span class="_ _0"></span>如不<span class="_ _0"></span>核准<span class="_ _0"></span>向教<span class="_ _0"></span>师说<span class="_ _0"></span>明理<span class="_ _0"></span>由,<span class="_ _0"></span>学院<span class="_ _0"></span>如核<span class="_ _0"></span>准则<span class="_ _0"></span>通知<span class="_ _0"></span>申请<span class="_ _0"></span>教师<span class="_ _0"></span>、报<span class="_ _0"></span>教务<span class="_ _0"></span>处备<span class="_ _0"></span>案。<span class="_ _0"></span>教务<span class="_ _0"></span>处汇<span class="_ _0"></span>集</div><div class="t m0 x2 h4 y7 ff1 fs1 fc0 sc1 ls0 ws0">全部<span class="_ _0"></span>可开<span class="_ _0"></span>的选<span class="_ _0"></span>修课<span class="_ _0"></span>,排<span class="_ _0"></span>定各<span class="_ _0"></span>专业<span class="_ _0"></span>在下<span class="_ _0"></span>一学<span class="_ _0"></span>年可<span class="_ _0"></span>供选<span class="_ _0"></span>择的<span class="_ _0"></span>选修<span class="_ _0"></span>课程<span class="_ _0"></span>,并<span class="_ _0"></span>发到<span class="_ _0"></span>各学<span class="_ _0"></span>院,<span class="_ _0"></span>由各<span class="_ _0"></span>学</div><div class="t m0 x2 h4 y8 ff1 fs1 fc0 sc1 ls0 ws0">院通<span class="_ _0"></span>知<span class="_ _0"></span>学生<span class="_ _0"></span>,<span class="_ _0"></span>学生<span class="_ _0"></span>应<span class="_ _0"></span>修的<span class="_ _0"></span>全<span class="_ _0"></span>部选<span class="_ _0"></span>修<span class="_ _0"></span>课程<span class="_ _0"></span>不<span class="_ _0"></span>少于<span class="_ _1"> </span><span class="ff2">5<span class="_ _2"> </span></span>门、<span class="_ _0"></span>不<span class="_ _0"></span>多于<span class="_ _3"> </span><span class="ff2">8<span class="_ _2"> </span></span>门<span class="_ _0"></span>,每<span class="_ _0"></span>学<span class="_ _0"></span>期的<span class="_ _0"></span>选<span class="_ _0"></span>修课<span class="_ _0"></span>程<span class="_ _0"></span>不少</div><div class="t m0 x2 h4 y9 ff1 fs1 fc0 sc1 ls0 ws0">于<span class="_ _2"> </span><span class="ff2">1<span class="_ _2"> </span></span>门<span class="_ _0"></span>、不<span class="_ _0"></span>多<span class="_ _0"></span>于<span class="_ _2"> </span><span class="ff2">3<span class="_ _2"> </span></span>门<span class="_ _0"></span>。学<span class="_ _0"></span>生<span class="_ _0"></span>选好<span class="_ _0"></span>后<span class="_ _0"></span>由各<span class="_ _0"></span>个<span class="_ _0"></span>学院<span class="_ _0"></span>反<span class="_ _0"></span>馈到<span class="_ _0"></span>教<span class="_ _0"></span>务处<span class="_ _0"></span>,<span class="_ _0"></span>教务<span class="_ _0"></span>处<span class="_ _0"></span>根据<span class="_ _0"></span>选<span class="_ _0"></span>修的<span class="_ _0"></span>情<span class="_ _0"></span>况指<span class="_ _0"></span>定</div><div class="t m0 x2 h4 ya ff1 fs1 fc0 sc1 ls0 ws0">定教师、并通知各学院,各学院则通知学生、教师。</div><div class="t m0 x4 h4 yb ff1 fs1 fc0 sc1 ls0 ws0">全部通<span class="_ _0"></span>知都应<span class="_ _0"></span>该以文<span class="_ _0"></span>件方式<span class="_ _0"></span>完成,<span class="_ _0"></span>所有相<span class="_ _0"></span>关人员<span class="_ _0"></span>和单位<span class="_ _0"></span>都能查<span class="_ _0"></span>询到排<span class="_ _0"></span>课的进<span class="_ _0"></span>展,在<span class="_ _0"></span>进</div><div class="t m0 x2 h4 yc ff1 fs1 fc0 sc1 ls0 ws0">入下<span class="_ _0"></span>一步<span class="_ _0"></span>之前<span class="_ _0"></span>相关<span class="_ _0"></span>的选<span class="_ _0"></span>择都<span class="_ _0"></span>可以<span class="_ _0"></span>被相<span class="_ _0"></span>关人<span class="_ _0"></span>员修<span class="_ _0"></span>改,<span class="_ _0"></span>进入<span class="_ _0"></span>下一<span class="_ _0"></span>步之<span class="_ _0"></span>后则<span class="_ _0"></span>不可<span class="_ _0"></span>修改<span class="_ _0"></span>。每<span class="_ _0"></span>次修<span class="_ _0"></span>改</div><div class="t m0 x2 h4 yd ff1 fs1 fc0 sc1 ls0 ws0">也应当向有关部门和人员发更改通知。</div><div class="t m0 x4 h4 ye ff1 fs1 fc0 sc1 ls0 ws0">所有的<span class="_ _0"></span>部门和<span class="_ _0"></span>人员都<span class="_ _0"></span>必须先<span class="_ _0"></span>登录,<span class="_ _0"></span>输入帐<span class="_ _0"></span>号和密<span class="_ _0"></span>码后才<span class="_ _0"></span>能使用<span class="_ _0"></span>该系统<span class="_ _0"></span>,并由<span class="_ _0"></span>教务处<span class="_ _0"></span>管</div><div class="t m0 x2 h4 yf ff1 fs1 fc0 sc1 ls0 ws0">理教<span class="_ _0"></span>师和<span class="_ _0"></span>学院<span class="_ _0"></span>,由<span class="_ _0"></span>学院<span class="_ _0"></span>管理<span class="_ _0"></span>学生<span class="_ _0"></span>和班<span class="_ _0"></span>级,<span class="_ _0"></span>由教<span class="_ _0"></span>务处<span class="_ _0"></span>和学<span class="_ _0"></span>院共<span class="_ _0"></span>同管<span class="_ _0"></span>理课<span class="_ _0"></span>程。<span class="_ _0"></span>所有<span class="_ _0"></span>的部<span class="_ _0"></span>门和<span class="_ _0"></span>人</div><div class="t m0 x2 h4 y10 ff1 fs1 fc0 sc1 ls0 ws0">员都可以查询与其相关的信息。</div><div class="t m0 x2 h4 y11 ff1 fs1 fc0 sc0 ls0 ws0">二、导出数据流图</div><div class="t m0 x3 h4 y12 ff1 fs1 fc0 sc1 ls0 ws0">根据以上“需求说明”通过自顶向下、逐步求精的方法可得到数据流图。</div></div></div><div class="pi" data-data='{"ctm":[1.611850,0.000000,0.000000,1.611850,0.000000,0.000000]}'></div></div>
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