book_text9.htm

深入编程内幕vc++ 非常适合处学者学习

            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">应用进行数据库访问的基础。引擎本身的数据库格式为</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MDB</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">，也支持对目前流行的绝大多数数据库格式的访问，当然</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MDB</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">是数据库引擎中效率最高的数据库。</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt; mso-tab-count: 1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; 
            </SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">如果您使用客户机</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">/</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">服务器模型的话，建议您使用</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">ODBC</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">方案；如果您希望采用</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MDB</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">格式的数据库，或者利用数据库引擎的速度，那么</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">DAO</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">是更好的选择。</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <H3 style="mso-line-height-alt: 1.3pt"><A name=_Toc419881643><SPAN 
            lang=EN-US 
            style="FONT-FAMILY: 宋体; mso-hansi-font-family: MS Sans Serif; mso-bookmark: _Toc419740461">4．2 
            使用MFC实现DAO技术</SPAN></A></H3>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; TEXT-INDENT: 25.5pt; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MFC</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">对所有的</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">DAO</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">对象都进行了封装。使用</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MFC</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">进行</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">DAO</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">编程，首先要为每一个打开的数据库文件提供一个数据库对象──</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CDaoDatabase</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">，由这个对象管理数据库的连接。然生成记录集对象──</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CDaoRecordset</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">，通过它来进行查询、操作、更新等等的工作。如果需要在程序中管理数据库的结构，则需要使用<SPAN 
            lang=EN-US>DAO当中的表结构信息对象CDaoTableInfo及字段定义对象</SPAN></SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CDaoFieldInfo</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">来进行获得或者改变数据库表结构的工作。</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CDaoDatabase</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">、</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CDaoRecordset</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">、</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CDaoTableDefInfo</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">、</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">CDaoFieldInfo</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">是使用</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MFC</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">进行</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">DAO</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">编程的最基本也是最常用的类。</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; TEXT-INDENT: 20pt; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">下面，我们通过一个实例来介绍如何使用</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MFC</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">的</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">DAO</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">类来进行数据库访问的工作。在这个实例当中，我们将在程序当中建立一个学生档案管理数据库，并通过对话框来添加、删除和浏览记录。我们首先看以下程序运行的情况。<SPAN 
            lang=EN-US><O:P> </O:P></SPAN></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; TEXT-INDENT: 20pt; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">我们将针对程序的功能依次介绍如何生成和使用数据库对象、记录集对象以及如何通过记录集来操纵数据库。我们将通过解释对数据库进行操作的源程序来介绍如何用</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MFC</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">来实现</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">DAO</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">技术。</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">下面介绍如何建库：<SPAN 
            lang=EN-US><O:P> </O:P></SPAN></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">首先新建一个数据库对象。<SPAN 
            lang=EN-US><O:P> </O:P></SPAN></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black">newDatabase 
            =<SPAN style="mso-spacerun: yes">&nbsp; </SPAN>new 
            CDaoDatabase;<O:P> </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black">newDatabase_&gt;Create(_T("stdfile.mdb"), 
            <O:P></O:P></SPAN></P>
            <P class=MsoNormal 
            style="MARGIN-LEFT: 3cm; WORD-BREAK: break-all; TEXT-INDENT: 1cm; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; BACKGROUND: #d9d9d9; FONT-FAMILY: 'Courier New'; mso-bidi-font-size: 10.0pt; mso-bidi-font-family: 'Times New Roman'; mso-shading: white; mso-pattern: gray-15 black"><SPAN 
            style="mso-spacerun: yes">&nbsp; </SPAN>dbLangGeneral, 
            dbVersion30);<O:P> </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">利用数据库引擎在磁盘上建立一个</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt">MDB</SPAN><SPAN 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">格式的数据库文件。</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal 
            style="WORD-BREAK: break-all; mso-line-height-alt: 1.3pt; mso-layout-grid-align: none; punctuation-wrap: simple"><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; FONT-FAMILY: 宋体; mso-bidi-font-size: 10.0pt; mso-hansi-font-family: 'MS Sans Serif'">stdfile.mdb是在磁盘上面建立的数据库文件的名字，</SPAN><SPAN 
            lang=EN-US 
            style="FONT-SIZE: 10.5pt; mso-bidi-font-size: 10.0pt"><O:P> 
            </O:P></SPAN></P>
            <P class=MsoNormal