﻿<?xml version="1.0" encoding="utf-8" standalone="yes"?><rss version="2.0" xmlns:dc="http://purl.org/dc/elements/1.1/" xmlns:trackback="http://madskills.com/public/xml/rss/module/trackback/" xmlns:wfw="http://wellformedweb.org/CommentAPI/" xmlns:slash="http://purl.org/rss/1.0/modules/slash/"><channel><title>BlogJava-bruce's sky-随笔分类-DB</title><link>http://www.blogjava.net/brucepeng/category/41573.html</link><description /><language>zh-cn</language><lastBuildDate>Sat, 05 Sep 2009 03:22:46 GMT</lastBuildDate><pubDate>Sat, 05 Sep 2009 03:22:46 GMT</pubDate><ttl>60</ttl><item><title>database link for Oracle: Users of Database Links</title><link>http://www.blogjava.net/brucepeng/archive/2009/09/05/293975.html</link><dc:creator>bruce.peng</dc:creator><author>bruce.peng</author><pubDate>Sat, 05 Sep 2009 02:42:00 GMT</pubDate><guid>http://www.blogjava.net/brucepeng/archive/2009/09/05/293975.html</guid><wfw:comment>http://www.blogjava.net/brucepeng/comments/293975.html</wfw:comment><comments>http://www.blogjava.net/brucepeng/archive/2009/09/05/293975.html#Feedback</comments><slash:comments>0</slash:comments><wfw:commentRss>http://www.blogjava.net/brucepeng/comments/commentRss/293975.html</wfw:commentRss><trackback:ping>http://www.blogjava.net/brucepeng/services/trackbacks/293975.html</trackback:ping><description><![CDATA[When creating the link, you determine which user should connect to the remote database to access the data. <br />
The following table explains the differences among the categories of users involved in database links:<br />
当创建link时，你必须是哪个user连接 remote database 访问数据<br />
下表解释了不同user 如何调用database link:<br />
<table width="567" border="0" cellpadding="2" cellspacing="2" height="1027">
    <tbody>
        <tr>
            <td><strong>&nbsp;User Type</strong><br />
            <br />
            usre 类型</td>
            <td><strong>Sample Link Creation Syntax</strong><br />
            <br />
            创建link的语法<br />
            </td>
        </tr>
        <tr>
            <td><strong>&nbsp;Connected user</strong>&nbsp; ---connetcted user 不是创建link的user，只是可以访问这个link的user<br />
            一个本地user可以通过指定username和pwd访问database link，那么他就是connected user。<br />
            system 通过public link 查询，这时connected user是system，并且remote数据库会连接到system schema</td>
            <td>&nbsp;CREATE PUBLIC DATABASE LINK hq USING 'hq';</td>
        </tr>
        <tr>
            <td><strong>&nbsp;Current use</strong>r&nbsp; --global user必须有 X.509 认证（一个SSL-authenticated enterprise user）并且这个user 必须可以调用这个database link。current user 是oracle security的一个方面。<br />
            <br />
            详情可以参见 oracle database advanced security. administrator 手册中的global security 相关信息</td>
            <td>&nbsp;CREATE PUBLIC DATABASE LINK hq CONNECT TO CURRENT_USER using 'hq';</td>
        </tr>
        <tr>
            <td><strong>&nbsp;Fixed user</strong>&nbsp; --当定义创建定义一个database link 时，Fixed user 的username/password 会出现在定义语句中。<br />
            当一个link中包含了fixed user的用户名和密码，那么这个用户名和密码将用于连接remote database.</td>
            <td>&nbsp;CREATE PUBLIC DATABASE LINK hq CONNECT TO jane IDENTIFIED BY doe USING 'hq';</td>
        </tr>
    </tbody>
</table>
<br />
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