chap10_9.htm

非常好的应用vc＋＋6.0进行相关网络程序开发的教程

    <p ALIGN="JUSTIFY">AfxMessageBox(&quot;Can't add DSN!&quot;);</p>
    <p ALIGN="JUSTIFY">return ;</p>
    <p ALIGN="JUSTIFY">}</p>
    <p ALIGN="JUSTIFY">TRY</p>
    <p ALIGN="JUSTIFY">{</p>
    <p ALIGN="JUSTIFY">db.Open(&quot;MYDB&quot;);</p>
    <blockquote>
      <blockquote>
        <p ALIGN="JUSTIFY">db.ExecuteSQL(&quot;CREATE TABLE OFFICES (OfficeID TEXT(4)&quot; </p>
        <p ALIGN="JUSTIFY">&quot;,OfficeName TEXT(10))&quot;); }</p>
      </blockquote>
    </blockquote>
    <p ALIGN="JUSTIFY">CATCH(CDBException, e)</p>
    <p ALIGN="JUSTIFY">{</p>
    <p ALIGN="JUSTIFY">AfxMessageBox(e-&gt;m_strError);</p>
    <p ALIGN="JUSTIFY">return;</p>
    <p ALIGN="JUSTIFY">}</p>
    <p ALIGN="JUSTIFY">END_CATCH</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">　</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">ExecuteSQL</font><font SIZE="3">执行了一个实实在在的</font><font FACE="Times New Roman" SIZE="3">SQL</font><font SIZE="3">语句</font><font FACE="Times New Roman" SIZE="3">CREATE</font><font SIZE="3">来创建表，看来用户应该找本</font><font FACE="Times New Roman" SIZE="3">SQL</font><font SIZE="3">方面的书研究研究。要注意一个数据库中的表名必须是唯一的，如果要创建的表已经存在，则</font><font FACE="Times New Roman" SIZE="3">ExecuteSQL</font><font SIZE="3">会产生一个异常。</font><font FACE="Times New Roman" SIZE="3"></p>
    <b><p ALIGN="JUSTIFY"></b></font><font color="#3973DE" FACE="Times New Roman" SIZE="3">10.9.3 
    </font><font color="#3973DE"><font SIZE="3">用</font><font FACE="Times New Roman" SIZE="3">DAO</font><font SIZE="3">创建表</font></font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">由于</font><font FACE="Times New Roman" SIZE="3">DAO</font><font SIZE="3">类直接支持</font><font FACE="Times New Roman" SIZE="3">DDL</font><font SIZE="3">，所以用</font><font FACE="Times New Roman" SIZE="3">DAO</font><font SIZE="3">类创建表比</font><font FACE="Times New Roman" SIZE="3">ODBC</font><font SIZE="3">容易。</font><font FACE="Times New Roman" SIZE="3">DAO</font><font SIZE="3">的</font><font FACE="Times New Roman" SIZE="3">CDaoTableDef</font><font SIZE="3">类提供了对表的结构的定义，该类提供了创建表的成员函数。</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">清单</font><font FACE="Times New Roman" SIZE="3">10.16</font><font SIZE="3">演示了一段用</font><font FACE="Times New Roman" SIZE="3">DAO</font><font SIZE="3">类创建表的例子。注意，若要使用这段代码，则应该包含</font><font FACE="Times New Roman" SIZE="3">afxdao.h</font><font SIZE="3">头文件。在该例中，先与一个</font><font FACE="Times New Roman" SIZE="3">FoxPro 2.5</font><font SIZE="3">数据库连接（实际上是一个目录），然后再构建一个</font><font FACE="Times New Roman" SIZE="3">CDaoTableDef</font><font SIZE="3">对象，接着调用</font><font FACE="Times New Roman" SIZE="3">CDaoTableDef :: Create</font><font SIZE="3">函数创建一个名为</font><font FACE="Times New Roman" SIZE="3">STUDENTS</font><font SIZE="3">的表</font><font FACE="Times New Roman" SIZE="3">(STUDENTS.DBF)</font><font SIZE="3">，调用</font><font FACE="Times New Roman" SIZE="3">CDaoTableDef :: CreateField</font><font SIZE="3">为该表创建了两字段，字段名分别是</font><font FACE="Times New Roman" SIZE="3">ID</font><font SIZE="3">和</font><font FACE="Times New Roman" SIZE="3">NAME</font><font SIZE="3">，类型分别是</font><font FACE="Times New Roman" SIZE="3">Integer</font><font SIZE="3">和</font><font FACE="Times New Roman" SIZE="3">dbText</font><font SIZE="3">，字段的长度分别为</font><font FACE="Times New Roman" SIZE="3">2</font><font SIZE="3">和</font><font FACE="Times New Roman" SIZE="3">10</font><font SIZE="3">个字节。最后调用</font><font FACE="Times New Roman" SIZE="3">CDaoTableDef :: Append</font><font SIZE="3">把新创建的表保存到数据库中。</font><font FACE="Times New Roman" SIZE="3"></p>
    </font><b><font SIZE="3"><p ALIGN="JUSTIFY">清单</font><font FACE="Times New Roman" SIZE="3">10.16 DAO</font><font SIZE="3">创建表的例子</font></b><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY">#include </font><font SIZE="3">“</font><font FACE="Times New Roman" SIZE="3">afxdao.h</font><font SIZE="3">”</font><font FACE="Times New Roman" SIZE="3"></p>
    <p ALIGN="JUSTIFY"><b>. . .</b></p>
    <p ALIGN="JUSTIFY">CDaoDatabase daoDb;</p>
    <p ALIGN="JUSTIFY">try</p>
    <p ALIGN="JUSTIFY">{</p>
    <p ALIGN="JUSTIFY">daoDb.Open(&quot;&quot;,FALSE,FALSE,&quot;FoxPro 
    2.5;DATABASE=d:\\zwin&quot;);</p>
    <p ALIGN="JUSTIFY">CDaoTableDef table(&amp;daoDb);</p>
    <p ALIGN="JUSTIFY">table.Create(&quot;STUDENTS&quot;);</p>
    <p ALIGN="JUSTIFY">table.CreateField(&quot;ID&quot;,dbInteger,2);</p>
    <p ALIGN="JUSTIFY">table.CreateField(&quot;NAME&quot;,dbText,10);</p>
    <p ALIGN="JUSTIFY">table.Append();</p>
    <p ALIGN="JUSTIFY">}</p>
    <p ALIGN="JUSTIFY">catch(CDaoException* e)</p>
    <p ALIGN="JUSTIFY">{</p>
    <p ALIGN="JUSTIFY">AfxMessageBox(e-&gt;</p>
    <p ALIGN="JUSTIFY">m_pErrorInfo-&gt;m_strDescription);</p>
    <p ALIGN="JUSTIFY">e-&gt;Delete();</p>
    <p ALIGN="JUSTIFY">return FALSE;</p>
    <p ALIGN="JUSTIFY">}</p>
    <p ALIGN="JUSTIFY"></font><font SIZE="3">关于</font><font FACE="Times New Roman" SIZE="3">CDaoDatabase :: Open</font><font SIZE="3">的说明请参见</font><font FACE="Times New Roman" SIZE="3">10.8.3</font><font SIZE="3">。注意一个数据库中的表名必须是唯一的，如果要创建的表已经存在，则</font><font FACE="Times New Roman" SIZE="3">CDaoTableDef :: Create</font><font SIZE="3">会产生一个异常。</font><font FACE="Times New Roman" SIZE="3"></p>
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