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<html xmlns="http://www.w3.org/TR/xhtml1/strict"> <head> <title>天极网</title> <meta http-equiv="Content-Type" content="text/html; charset=gb2312"></meta> <meta http-equiv="Pragma" content="no-cache"></meta> <meta http-equiv="expires" content="Mon,12 May 1998 00:36:05 GMT"></meta> <link rel="stylesheet" href="/xslimages/css/cpcw.css"></link> </head> <style>.nava { font-size: 9pt}.font1{font-size: 10.5pt}</style> <body bgcolor="#FFFFFF" topmargin="2"><table width="760" border="0" cellspacing="0" cellpadding="0" align="center"><tr><td width="20%" rowspan="3" valign="top" align="center"><table width="95%" border="1" cellspacing="0" cellpadding="0" height="60" bordercolorlight="#CCCCCC" bordercolordark="#FFFFFF"><tr valign="middle" align="center"><td><div align="center"><span class="nava">天极硬件，新闻及时<br>资料详尽，敬请关注<br><a href="/33554432/35651584/yingjian.htm">www.myhard.com</a></span></div></td></tr></table></td><td width="57%" valign="bottom" rowspan="3" align="center" height="60"><div 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href="/33554432/34603008/34668544/34669568/schoolinverse2.htm">程序方舟</a>→ <a href="/33554432/34603008/34668544/34669568/34669920/schoolinverse2.htm">经验技巧</a>→ <a href="/33554432/34603008/34668544/34669568/34669920/34669921/schoolinverse1.htm">DELPHI技巧</a>→ </span></span></td><td width="2%"></td></tr></table><table width="760" border="0" cellspacing="0" cellpadding="0" align="center"><tr><td colspan="3" valign="top" width="75%"><table width="98%" border="0" cellspacing="1" cellpadding="1" bgcolor="#000000"><tr bgcolor="#FFFFFF"><td width="100%" colspan="4" align="left"><table width="95%" align="center"><tr><td class="font1"><p align="center"><br><font size="3">在Delphi程序中操作大二分对象（BLOB）</font><br><span class="nava"><font color="#CC9933">2000-11-05· 李晓平 袁一林·yesky</font></span></p><span class="txt"><p align="right"><font face="Webdings">7</font><B><font color="red"> 1 <a href="130290_1.htm">2</a> <a href="130290_2.htm">3</a> <a href="130290_1.htm">下一页</a></font></B><font face="Webdings">8</font></p> 随着数据库及多媒体技术的发展，人们需要存储、处理的信息的种类越来越多。数据库中存储的数据不再只是文本、数字，而且还可能是图形、声音、视频等等，各式各样的类型。早期的数据库是无法处理这些类型的数据的。现在的数据库中为处理这些特殊格式的数据，设置了一种大二分对象（BLOB-Binary
Large OBject）。<br>
BLOB在数据库的表中实际上是以二进制数据的形式存放的。由于BLOB的特殊性，一般的程序都无法处理它。比如，如果在一张表中存在BLOB,当用Dattabase
Desktop（Delphi在带的数据库管理工具）打开它时，BLOB列将只显示BLOB字样。至于该列中实际存的是什么数据是单靠Database DeskTop是无法得到的。如果在我们编制的程序中，用DBGrid控件打开一个有BLOB字段的表，效果也一样。我们的程序无法直接显示、编辑以及插入BLOB字段。可见，常规的方法是不能满足要求的。<br>
如何处理BLOB字段，可以借鉴一些可视的桌面数据库的方法。如Access中，BLOB字段是可以通过双击该字段的方式打开。Access是通过OLE的方式实现BLOB数据的编辑及处理的，所以我们也可以在通过程序中设置OLE控件的方法来处理BLOB。下面，我们先讨论操作BLOB的关键问题，然后给出一个简单的例子。<br>
<b><br>
操作BLOB的关键</b><br>
要在程序中自如地操作BLOB数据，无非是解决以下几个问题：<br>
1. BLOB数据的入库操作<br>
2. BLOB数据的显示<br>
3. BLOB数据的编辑、修改<br>
由于数据的类型可能千变万化，所以，采用OLE方式是较方便的选择。我们可以在程序中放置一个OLE控件，用于显示、编辑各种BLOB数据。那么，问题的关键就是BLOB数据如何入库，以及数据库如何与OLE控件之间传递数据。<br>
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