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<ul class="list"><li class="listitem">火星拿拿：<a href="http://blog.csdn.net/muyannian/archive/2007/12/20/1956449.aspx#753909" Title="點擊查看《回復:郁悶，真的不知道自己到底喜歡什么》">加油呀，小母子，我覺得要把握自己的核心競爭力</a></li><li class="listitem">interim：<a href="http://blog.csdn.net/muyannian/archive/2007/11/21/1897139.aspx#744872" Title="點擊查看《回復:關于c#實現(xiàn)影音嗅探的問題》">探測的是程序自己的包吧？</a></li><li class="listitem">liliangjava：<a href="http://blog.csdn.net/muyannian/archive/2007/08/03/1723971.aspx#741130" Title="點擊查看《回復:Berkeley DB Java Edition 使用手冊》">太好了，正準備用這個呢，感謝樓主！！！！</a></li></ul>
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<script>function StorePage(){d=document;t=d.selection?(d.selection.type!='None'?d.selection.createRange().text:''):(d.getSelection?d.getSelection():'');void(keyit=window.open('http://www.365key.com/storeit.aspx?t='+escape(d.title)+'&u='+escape(d.location.href)+'&c='+escape(t),'keyit','scrollbars=no,width=475,height=575,left=75,top=20,status=no,resizable=yes'));keyit.focus();}</script><div class="post"> <div class="postTitle"> <script src="http://wz.csdn.net/javascripts/vote.js"></script><a href="http://blog.csdn.net/muyannian/archive/2007/12/11/1929712.aspx"><img src='/images/authorship.gif' border='0' width='15' height='13' /> Berkeley DB for C 使用手冊</a>  <script src="http://blog.csdn.net/count.aspx?ID=1929712&Type=Rank"></script> </div> <div class="postText"> <p align="center" style="text-align: center;" class="MsoNormal"><strong><em><span lang="EN-US" style="font-size: 24pt; font-family: TimesNewRomanPS-BoldItalicMT;">Berkeley DB for C</span></em></strong><span lang="EN-US" style="font-size: 10pt; font-family: TimesNewRomanPS-BoldItalicMT;"><o:p></o:p></span></p><p class="MsoNormal"><strong><span lang="EN-US" style="font-size: 16pt;"><!--[if !supportEmptyParas]--> <!--[endif]--><o:p></o:p></span></strong></p><h3><span style="font-family: 宋體;">簡單介紹</span><span lang="EN-US">Brekeley DB</span></h3><h3><span style="font-family: 宋體;">打開</span><span lang="EN-US">databases</span></h3><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span style="font-size: 10pt; font-family: 宋體; color: black;">在開打數(shù)據(jù)庫前必須通過<span lang="EN-US">db_create()方法來初始化一個db句柄, 然后你可以通過他的open方法來打開一個數(shù)據(jù)庫</span></span><span lang="EN-US" style="font-size: 10pt; font-family: TrebuchetMS; color: black;"><o:p></o:p></span></p><p class="MsoNormal"><span lang="EN-US"><!--[if !supportEmptyParas]--> <!--[endif]--><o:p></o:p></span></p><p class="MsoNormal"><span style="font-family: 宋體;">示例：</span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">#include <db.h><span style=""> </span>//</span><span style="font-size: 10pt; font-family: 宋體;">必要的包含文件</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">...<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB *dbp; /* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫結構句柄</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">u_int32_t flags; /* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫打開標志</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">int ret; /* </span><span style="font-size: 10pt; font-family: 宋體;">用來接收通過</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">db_create</span><span style="font-size: 10pt; font-family: 宋體;">來創(chuàng)建的數(shù)據(jù)庫是否成功</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">初始化結構體</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* </span><span style="font-size: 10pt; font-family: 宋體;">因為數(shù)據(jù)庫沒有在環(huán)境中打開</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* </span><span style="font-size: 10pt; font-family: 宋體;">所以環(huán)境指針為</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">null. */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">ret = db_create(&dbp, NULL, 0);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">if (ret != 0) {<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">錯誤處理</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">}<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫打開標志</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">flags = DB_CREATE; /* </span><span style="font-size: 10pt; font-family: 宋體;">如果數(shù)據(jù)庫不存在的化則創(chuàng)建一個新的</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">*/<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">打開數(shù)據(jù)庫</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">ret = dbp->open(dbp, /* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫結構指針</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">NULL, /* </span><span style="font-size: 10pt; font-family: 宋體;">事務處理指針</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">"my_db.db", /* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫名</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">NULL, /* Optional logical database name */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB_BTREE, /* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫訪問方式</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">flags, /* </span><span style="font-size: 10pt; font-family: 宋體;">打開標識</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">0); /* </span><span style="font-size: 10pt; font-family: 宋體;">文件模式</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> (</span><span style="font-size: 10pt; font-family: 宋體;">使用默認的</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">) */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">if (ret != 0) {<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">錯誤處理</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">}<o:p></o:p></span></p><h3><span style="font-family: 宋體;">關閉</span><span lang="EN-US">databases</span></h3><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span style="font-family: 宋體;">一旦你使用完畢某個數(shù)據(jù)庫，你必須通過</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB->close()</span><span style="font-size: 10pt; font-family: 宋體;">來關閉他。除非你再次打開他否則關閉后的數(shù)據(jù)庫是不能在使用的。在關閉數(shù)據(jù)庫之前請確保與之相關的游標先關閉，否則會有很多想不到的后果。關閉數(shù)據(jù)庫后很多緩存在內(nèi)存中的數(shù)據(jù)會被同步到你的硬盤中去，而且你也可以隨時通過</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB->sync()</span><span style="font-family: 宋體;">方法來隨時同步數(shù)據(jù)庫。</span></p><p align="left" style="text-align: left;" class="MsoNormal"><span style="font-family: 宋體;">使用示例：</span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">#include <db.h><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">...<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB *dbp; /* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫句柄</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">...<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/*<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* </span><span style="font-size: 10pt; font-family: 宋體;">在這里進行一些數(shù)據(jù)庫有關的操作</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">*/<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">...<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">當你不在使用他的時候關閉他</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">. */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">if (dbp != NULL)<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">dbp->close(dbp, 0);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US"><!--[if !supportEmptyParas]--> <!--[endif]--><o:p></o:p></span></p><h3><span style="font-family: 宋體;">數(shù)據(jù)庫打開表識（</span><span lang="EN-US">flags</span><span style="font-family: 宋體;">）</span></h3><p class="MsoNormal"><span style="font-family: 宋體;">如果在打開數(shù)據(jù)庫的時候使用多個標識則可以通過按位或來添加多個標示</span></p><p class="MsoNormal"><span style="font-family: 宋體;">示例：</span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 9pt; font-family: Courier;">u_int32_t open_flags = DB_CREATE | DB_EXCL;</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p class="MsoNormal"><span lang="EN-US"><!--[if !supportEmptyParas]--> <!--[endif]--><o:p></o:p></span></p><p style="margin-left: 21pt; text-indent: -21pt;" class="MsoNormal"><!--[if !supportLists]--><span lang="EN-US" style="font-family: Wingdings;">l<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span><!--[endif]--><span style="font-family: 宋體;">標示說明：</span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB_CREATE</span><span style="font-size: 10pt; font-family: 宋體;">：當數(shù)據(jù)不存在的時候創(chuàng)建一個新的</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB_EXCL:</span><span style="font-size: 10pt; font-family: 宋體;">創(chuàng)建專用數(shù)據(jù)庫，如果數(shù)據(jù)庫已經(jīng)存在則將會打開失敗，這個標識只能與</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB_CREATE</span><span style="font-size: 10pt; font-family: 宋體;">聯(lián)合使用</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB_RDONLY</span><span style="font-size: 10pt; font-family: 宋體;">：以只讀方式打開數(shù)據(jù)庫，所有的寫操作都被禁止。</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB_TRUNCATE</span><span style="font-size: 10pt; font-family: 宋體;">：打開數(shù)據(jù)庫的同時清空數(shù)據(jù)庫中原有的記錄。</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><!--[if !supportEmptyParas]--> <!--[endif]--><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span style="font-size: 10pt; font-family: 宋體;">下面這些方法可能會對你管理數(shù)據(jù)庫有用</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="margin-left: 21pt; text-align: left; text-indent: -21pt;" class="MsoNormal"><!--[if !supportLists]--><span lang="EN-US" style="font-size: 10pt; font-family: Wingdings;">l<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span><!--[endif]--><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB->get_open_flags()</span><span style="font-size: 10pt; font-family: 宋體;">：返回當前的數(shù)據(jù)庫打開標識，如果在打開數(shù)據(jù)庫前調(diào)用此方法會出錯。</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="margin-left: 21pt; text-align: left;" class="MsoNormal"><span style="font-size: 10pt; font-family: 宋體;">使用示例：</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">#include <db.h><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">...<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB *dbp;<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">u_int32_t open_flags;<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* Database open and subsequent operations omitted for clarity */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">dbp->get_open_flags(dbp, &open_flags);<o:p></o:p></span></p><p align="left" style="margin-left: 21pt; text-align: left; text-indent: -21pt;" class="MsoNormal"><!--[if !supportLists]--><span lang="EN-US" style="font-size: 10pt; font-family: Wingdings;">l<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span><!--[endif]--><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB->remove()<o:p></o:p></span></p><p align="left" style="margin-left: 21pt; text-align: left;" class="MsoNormal"><span style="font-size: 10pt; font-family: 宋體;">如果一個數(shù)據(jù)庫已經(jīng)不再需要，則可以使用這個方法來刪除。</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="margin-left: 21pt; text-align: left;" class="MsoNormal"><span style="font-size: 10pt; font-family: 宋體;">示例：</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">#include <db.h><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">...<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB *dbp;<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* Database open and subsequent operations omitted for clarity */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">dbp->remove(dbp, /* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫句柄</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">"mydb.db", /* </span><span style="font-size: 10pt; font-family: 宋體;">要移除的數(shù)據(jù)庫</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">NULL, /* Database to remove. This is<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* NULL so the entire file is<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* removed. */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">0); /* Flags. None used. */<o:p></o:p></span></p><p align="left" style="margin-left: 21pt; text-align: left; text-indent: -21pt;" class="MsoNormal"><!--[if !supportLists]--><span lang="EN-US" style="font-size: 10pt; font-family: Wingdings;">l<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span><!--[endif]--><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB->rename()<o:p></o:p></span></p><p align="left" style="margin-left: 21pt; text-align: left;" class="MsoNormal"><span style="font-size: 10pt; font-family: 宋體;">給目標數(shù)據(jù)庫改名，不要試圖給一個已經(jīng)打開了的數(shù)據(jù)庫改名，那樣會出錯的。</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="margin-left: 21pt; text-align: left;" class="MsoNormal"><span style="font-size: 10pt; font-family: 宋體;">使用示例：</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">#include <db.h><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">...<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB *dbp;<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* Database open and subsequent operations omitted for clarity */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">dbp->rename(dbp, /* Database pointer */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">"mydb.db", /* </span><span style="font-size: 10pt; font-family: 宋體;">要被改名的數(shù)據(jù)庫</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">NULL, /* Database to rename. This is<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* NULL so the entire file is<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* renamed. */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">"newdb.db", /* </span><span style="font-size: 10pt; font-family: 宋體;">新的數(shù)據(jù)庫名</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">0);<o:p></o:p></span></p><p align="left" style="margin-left: 21pt; text-align: left; text-indent: -21pt;" class="MsoNormal"><!--[if !supportLists]--><span lang="EN-US" style="font-size: 10pt; font-family: Wingdings;">l<span style="font-family: "Times New Roman"; font-style: normal; font-variant: normal; font-weight: normal; font-size: 7pt; line-height: normal; font-size-adjust: none; font-stretch: normal;"> </span></span><!--[endif]--><span style="font-size: 10pt; font-family: 宋體;">與錯誤報告有關的幾個函數(shù)</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">set_errcall():</span><span style="font-size: 10pt; font-family: 宋體;">設置出錯的時候調(diào)用的函數(shù)</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">set_errfile():</span><span style="font-size: 10pt; font-family: 宋體;">設置出錯的時候</span><span style="font-size: 10pt; font-family: Courier;"> </span><span style="font-size: 10pt; font-family: 宋體;">把錯誤信息寫進去的文件指針（</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">file *</span><span style="font-size: 10pt; font-family: 宋體;">）</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">set_errpfx():</span><span style="font-size: 10pt; font-family: 宋體;">設置有數(shù)據(jù)庫產(chǎn)生的錯誤類型</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">err():</span><span style="font-size: 10pt; font-family: 宋體;">產(chǎn)生一個錯誤，如果指定了錯誤的回調(diào)函數(shù)或文件指針則把錯誤發(fā)送給相應的處理方法或文件，否則發(fā)送到標準出錯。</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">errx():</span><span style="font-size: 10pt; font-family: 宋體;">與</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">err()</span><span style="font-size: 10pt; font-family: 宋體;">雷同</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span style="font-size: 10pt; font-family: 宋體;">除此之外你可以通過</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">db_strerror()</span><span style="font-size: 10pt; font-family: 宋體;">來直接的返回錯誤代號。</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span style="font-size: 10pt; font-family: 宋體;">使用示例：</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/*<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* Function called to handle any database error messages<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* issued by DB.<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">*/<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">void<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">my_error_handler(const char *error_prefix, char *msg)<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">{<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/*<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* </span><span style="font-size: 10pt; font-family: 宋體;">相關的錯誤處理</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">*/<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">}<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: TrebuchetMS;"><span style=""> </span></span><span style="font-size: 10pt; font-family: 宋體;">注冊錯誤回調(diào)函數(shù)的方法如下<span lang="EN-US"><o:p></o:p></span></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><!--[if !supportEmptyParas]--> <!--[endif]--><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">#include <db.h><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">#include <stdio.h><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">...<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB *dbp;<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">int ret;<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/*<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* </span><span style="font-size: 10pt; font-family: 宋體;">為錯誤創(chuàng)建一個初始化的環(huán)境</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">*/<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">ret = db_create(&dbp, NULL, 0);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">if (ret != 0) {<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">fprintf(stderr, "%s: %s\n", "my_program",<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">db_strerror(ret));//</span><span style="font-size: 10pt; font-family: 宋體;">直接輸出錯誤信息</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">return(ret);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">}<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">設置回調(diào)函數(shù)</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">dbp->set_errcall(dbp, my_error_handler);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">dbp->set_errpfx(dbp, "my_example_program");//</span><span style="font-size: 10pt; font-family: 宋體;">設置回調(diào)前綴</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><!--[if !supportEmptyParas]--> <!--[endif]--><o:p></o:p></span></p><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><!--[if !supportEmptyParas]--> <!--[endif]--><o:p></o:p></span></p><p align="left" style="margin-left: 21pt; text-align: left;" class="MsoNormal"><span style="font-size: 10pt; font-family: 宋體;">發(fā)出錯誤信息示例：</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left; text-indent: 21pt;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">ret = dbp->open(dbp,<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">NULL,<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">"mydb.db",<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">NULL,<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB_BTREE,<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB_CREATE,<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">0);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">if (ret != 0) {<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">dbp->err(dbp, ret,<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">"Database open failed: %s", "mydb.db");//</span><span style="font-size: 10pt; font-family: 宋體;">發(fā)送錯誤信息</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">return(ret);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">}<o:p></o:p></span></p><h3><span style="font-family: 宋體;">數(shù)據(jù)庫環(huán)境管理</span><span lang="EN-US" style=""><o:p></o:p></span></h3><p class="MsoNormal"><span lang="EN-US"><span style=""> </span></span><span style="font-family: 宋體;">要想設置數(shù)據(jù)庫環(huán)境，首先你需要創(chuàng)建一個環(huán)境句柄并且打開他，在打開的時候你必須確保存在指定的目錄，同樣你頁可以設置環(huán)境所使用的內(nèi)存</span><span lang="EN-US">cache.</span></p><p class="MsoNormal"><span lang="EN-US"><span style=""> </span></span><span style="font-family: 宋體;">使用示例：</span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">#include <db.h><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">...<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB_ENV *myEnv; /* db</span><span style="font-size: 10pt; font-family: 宋體;">環(huán)境結構句柄</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB *dbp; /* db</span><span style="font-size: 10pt; font-family: 宋體;">結構句柄</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">u_int32_t db_flags; /* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫打開標識</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">u_int32_t env_flags; /* </span><span style="font-size: 10pt; font-family: 宋體;">環(huán)境打開標識</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">int ret; /* </span><span style="font-size: 10pt; font-family: 宋體;">用來存儲打開結果（成功還是失敗）</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/*<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span style="font-size: 10pt; font-family: 宋體;">創(chuàng)建一個數(shù)據(jù)庫環(huán)境</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">*/<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">ret = db_env_create(&myEnv, 0);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">if (ret != 0) {<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">//</span><span style="font-size: 10pt; font-family: 宋體;">錯誤處理</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">return -1;<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">}<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">打開環(huán)境</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">. */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">env_flags = DB_CREATE | /* </span><span style="font-size: 10pt; font-family: 宋體;">如果環(huán)境不存在則創(chuàng)建一個新的</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">*/<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB_INIT_MPOOL; /* </span><span style="font-size: 10pt; font-family: 宋體;">初始化內(nèi)存大小</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">. */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">ret = myEnv->open(myEnv, /* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫環(huán)境指針</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">"/export1/testEnv", /* </span><span style="font-size: 10pt; font-family: 宋體;">環(huán)境目錄</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">env_flags, /* </span><span style="font-size: 10pt; font-family: 宋體;">打開標識</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">0); /* File mode (default) */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">if (ret != 0) {<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">fprintf(stderr, "Environment open failed: %s", db_strerror(ret));<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">//</span><span style="font-size: 10pt; font-family: 宋體;">錯誤處理</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">return -1;<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">}<o:p></o:p></span></p><p class="MsoNormal"><span lang="EN-US"><!--[if !supportEmptyParas]--> <!--[endif]--><o:p></o:p></span></p><p style="text-indent: 21pt;" class="MsoNormal"><span style="font-family: 宋體;">一但打開一個數(shù)據(jù)庫環(huán)境后，你就可以通過他來打開數(shù)據(jù)庫。通常情況下數(shù)據(jù)庫默認存儲在環(huán)境的根目錄或其相對路徑</span></p><p class="MsoNormal"><span style="font-family: 宋體;">使用示例：</span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/*<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* </span><span style="font-size: 10pt; font-family: 宋體;">創(chuàng)建數(shù)據(jù)庫</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">*/<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">ret = db_create(&dbp, myEnv, 0);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">if (ret != 0) {<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* Error handling goes here */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">}<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫打開標志</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">db_flags = DB_CREATE; /* If the database does not exist,<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* create it.*/<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">打開數(shù)據(jù)庫</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">ret = dbp->open(dbp, /* db</span><span style="font-size: 10pt; font-family: 宋體;">結構指針</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">NULL, /* </span><span style="font-size: 10pt; font-family: 宋體;">事務處理指針</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">"my_db.db", /* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫名</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">NULL, /* Optional logical database name */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DB_BTREE, /* </span><span style="font-size: 10pt; font-family: 宋體;">數(shù)據(jù)庫訪問方式</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">db_flags, /* </span><span style="font-size: 10pt; font-family: 宋體;">打開標識符</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">0); /* File mode (using defaults) */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">if (ret != 0) {<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">錯誤處理</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"> */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">}<o:p></o:p></span></p><p class="MsoNormal"><span lang="EN-US"><!--[if !supportEmptyParas]--> <!--[endif]--><o:p></o:p></span></p><p class="MsoNormal"><span lang="EN-US"><span style=""> </span></span><span style="font-family: 宋體;">當你使用完一個環(huán)境后必須關閉他，請確保在關閉一個數(shù)據(jù)庫環(huán)境前先關閉所有數(shù)據(jù)庫。</span></p><p class="MsoNormal"><span style="font-family: 宋體;">使用示例：</span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/*<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">* </span><span style="font-size: 10pt; font-family: 宋體;">關閉數(shù)據(jù)庫和環(huán)境</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;"><o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">*/<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">if (dbp != NULL) {<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">dbp->close(dbp, 0);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">}<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">if (myEnv != NULL) {<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">myEnv->close(myEnv, 0);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">}<o:p></o:p></span></p><h3><span style="font-family: 宋體;">使用記錄</span></h3><p class="MsoNormal"><span style="font-family: 宋體;">每條數(shù)據(jù)庫記錄是由兩個</span><span lang="EN-US">DBT</span><span style="font-family: 宋體;">結構體所組成，一個代表鍵名</span><span lang="EN-US">(key),</span><span style="font-family: 宋體;">一個代表鍵值</span><span lang="EN-US">(value);</span></p><p class="MsoNormal"><span style="font-family: 宋體;">為了存儲數(shù)據(jù)我們只需要拿一個指針指向這段數(shù)據(jù)的首地址，并且標識出這段數(shù)據(jù)的長度就行了。具體使用示例如下：</span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DBT key, data; //</span><span style="font-size: 10pt; font-family: 宋體;">分別定義</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">key</span><span style="font-size: 10pt; font-family: 宋體;">和</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">value<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">float money = 122.45;<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">char *description = "Grocery bill.";<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">/* </span><span style="font-size: 10pt; font-family: 宋體;">開始使用</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DBT</span><span style="font-size: 10pt; font-family: 宋體;">的時候給</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">DBT</span><span style="font-size: 10pt; font-family: 宋體;">清</span><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">0 */<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">memset(&key, 0, sizeof(DBT));<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">memset(&data, 0, sizeof(DBT));<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">key.data = &money;<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">key.size = sizeof(float);<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">data.data = description;<o:p></o:p></span></p><p align="left" style="text-align: left;" class="MsoNormal"><span lang="EN-US" style="font-size: 10pt; font-family: Courier;">data.size = strlen(description) + 1;<o:p></o:p></span></p><p class="MsoNormal"><span lang="EN-US"><!--[if !supportEmptyParas]--> <!--[endif]--><o:p></o:p></span></p><p class="MsoNormal"><span style="font-family: 宋體;">為了能夠得到這條記錄，可以通過</span><span lang="EN-US">void</span><span style="font-family: 宋體;">指針指向</span><span lang="EN-US">DBT.</span></p><p class="MsoNormal"><span style="font-family: 宋體;">某些系統(tǒng)的</span><span lang="EN-US">float</span><span style="font-family: 宋體;">和</span><span lang="EN-US">struct</span><span style="font-family: 宋體;">類型的內(nèi)存對齊方式比較特殊，為了兼容性，應該使用</span><span lang="EN-US">Dbt</span><span style="font-family: 宋體;">的</span><span lang="EN-US">set_ulen</span><span style="font-family: 宋體;">函數(shù)設置內(nèi)存長度，并且用</span><span lang="EN-US">set_flag(DB_DBT_USERMEM)</span><span style="font-family: 宋體;">函數(shù)注明使用</span><span lang="EN-US">BDB</span><span style="font-family: 宋體;">的內(nèi)存處理方式</span><span lang="EN-US">.</span></p><p class="MsoNormal"><span style="font-family: 宋體;">只有在獲取數(shù)據(jù)的時候，才需要</span><span lang="EN-US">ulen</span><span style="font-family: 宋體;">的值。</span><span lang="EN-US">get()</span><span style="font-family: 宋體;">操作后，</span><span lang="EN-US">DBT</span><span style="font-family: 宋體;">的</span><span lang="EN-US">sizefield</span><span style="font-family: 宋體;">會設置為</span><span lang="EN-US">data</span><span style="font-family: 宋體;">的實際大小。可以通過設置</span><span lang="EN-US">flag</span><span style="font-family: 宋體;">為</span><span lang="EN-US">0</span><span style="font-family: 宋體;">，獲得</span><span lang="EN-US">data</span><span style="font-family: 宋體;">的實際大小。如果設置了</span><span lang="EN-US">flag</span><span style="font-family: 宋體;">為</span><span lang="EN-US">DB_DBT_USERMEM</span><span style="font-family: 宋體;">，那么必須使用</span><span lang="EN-US">try-catch</span><span style="font-family: 宋體;">模板包圍</span><span lang="EN-US">get()</span><span style="font-family: 宋體;">操作，如果返回的</span><span lang="?? 快捷鍵說明
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