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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<html>
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<head>
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<meta http-equiv="content-type" content="text/html; charset=UTF-8">
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<title>Selects the default database for database queries</title>
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</head>
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<body class="docs"><div id="layout">
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<div id="layout-content"><div id="function.maxdb-select-db" class="refentry">
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<div class="refnamediv">
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<h1 class="refname">maxdb_select_db</h1>
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<h1 class="refname">maxdb::select_db</h1>
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<p class="verinfo">(PECL maxdb >= 1.0)</p><p class="refpurpose"><span class="refname">maxdb_select_db</span> -- <span class="refname">maxdb::select_db</span> — <span class="dc-title">Selects the default database for database queries</span></p>
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</div>
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<div class="refsect1 description" id="refsect1-function.maxdb-select-db-description">
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<h3 class="title">说明</h3>
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<div class="methodsynopsis dc-description">
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<span class="methodname"><strong>maxdb_select_db</strong></span>
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( <span class="methodparam"><span class="type">resource</span> <code class="parameter">$link</code></span>
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, <span class="methodparam"><span class="type">string</span> <code class="parameter">$dbname</code></span>
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) : <span class="type">bool</span></div>
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<p class="para rdfs-comment">
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The <span class="function"><strong>maxdb_select_db()</strong></span> function selects the default
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database (specified by the <code class="parameter">dbname</code> parameter) to be
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used when performing queries against the database connection
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represented by the <code class="parameter">link</code> parameter.
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</p>
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<blockquote class="note"><p><strong class="note">Note</strong>:
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<p class="para">
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This function should only be used to change the default database for the connection.
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You can select the default database with 4th parameter in <span class="function"><a href="maxdb_connect.html" class="function">maxdb_connect()</a></span>.
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</p>
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</p></blockquote>
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</div>
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<div class="refsect1 returnvalues" id="refsect1-function.maxdb-select-db-returnvalues">
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<h3 class="title">返回值</h3>
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<p class="para">
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成功时返回 <strong><code>TRUE</code></strong>， 或者在失败时返回 <strong><code>FALSE</code></strong>。
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</p>
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</div>
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<div class="refsect1 examples" id="refsect1-function.maxdb-select-db-examples">
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<h3 class="title">范例</h3>
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<div class="example" id="example-1400">
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<p><strong>Example #1 面向对象风格</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$maxdb </span><span style="color: #007700">= new </span><span style="color: #0000BB">maxdb</span><span style="color: #007700">(</span><span style="color: #DD0000">"localhost"</span><span style="color: #007700">, </span><span style="color: #DD0000">"MONA"</span><span style="color: #007700">, </span><span style="color: #DD0000">"RED"</span><span style="color: #007700">, </span><span style="color: #DD0000">"DEMODB"</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* check connection */<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">maxdb_connect_errno</span><span style="color: #007700">()) {<br /> </span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"Connect failed: %s\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">maxdb_connect_error</span><span style="color: #007700">());<br /> exit();<br />}<br /><br /></span><span style="color: #FF8000">/* return name of current default database */<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">$maxdb</span><span style="color: #007700">-></span><span style="color: #0000BB">query</span><span style="color: #007700">(</span><span style="color: #DD0000">"SELECT SERVERDB FROM USERS WHERE USERNAME='MONA'"</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$row </span><span style="color: #007700">= </span><span style="color: #0000BB">$result</span><span style="color: #007700">-></span><span style="color: #0000BB">fetch_row</span><span style="color: #007700">();<br /> </span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"Default database is %s.\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$row</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">]);<br /> </span><span style="color: #0000BB">$result</span><span style="color: #007700">-></span><span style="color: #0000BB">close</span><span style="color: #007700">();<br />}<br /><br /></span><span style="color: #FF8000">/* change db to non existing db */<br /></span><span style="color: #0000BB">$maxdb</span><span style="color: #007700">-></span><span style="color: #0000BB">select_db</span><span style="color: #007700">(</span><span style="color: #DD0000">"XXXXXXXX"</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* return name of current default database */<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">$maxdb</span><span style="color: #007700">-></span><span style="color: #0000BB">query</span><span style="color: #007700">(</span><span style="color: #DD0000">"SELECT SERVERDB FROM USERS WHERE USERNAME='MONA'"</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$row </span><span style="color: #007700">= </span><span style="color: #0000BB">$result</span><span style="color: #007700">-></span><span style="color: #0000BB">fetch_row</span><span style="color: #007700">();<br /> </span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"Default database is %s.\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$row</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">]);<br /> </span><span style="color: #0000BB">$result</span><span style="color: #007700">-></span><span style="color: #0000BB">close</span><span style="color: #007700">();<br />}<br /><br /></span><span style="color: #0000BB">$maxdb</span><span style="color: #007700">-></span><span style="color: #0000BB">close</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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<div class="example" id="example-1401">
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<p><strong>Example #2 过程化风格</strong></p>
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<div class="example-contents">
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<div class="phpcode"><pre><span style="color: #000000">
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<span style="color: #0000BB"><?php<br />$link </span><span style="color: #007700">= </span><span style="color: #0000BB">maxdb_connect</span><span style="color: #007700">(</span><span style="color: #DD0000">"localhost"</span><span style="color: #007700">, </span><span style="color: #DD0000">"MONA"</span><span style="color: #007700">, </span><span style="color: #DD0000">"RED"</span><span style="color: #007700">, </span><span style="color: #DD0000">"DEMODB"</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* check connection */<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">maxdb_connect_errno</span><span style="color: #007700">()) {<br /> </span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"Connect failed: %s\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">maxdb_connect_error</span><span style="color: #007700">());<br /> exit();<br />}<br /><br /></span><span style="color: #FF8000">/* return name of current default database */<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">maxdb_query</span><span style="color: #007700">(</span><span style="color: #0000BB">$link</span><span style="color: #007700">, </span><span style="color: #DD0000">"SELECT SERVERDB FROM USERS WHERE USERNAME='MONA'"</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$row </span><span style="color: #007700">= </span><span style="color: #0000BB">maxdb_fetch_row</span><span style="color: #007700">(</span><span style="color: #0000BB">$result</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"Default database is %s.\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$row</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">]);<br /> </span><span style="color: #0000BB">maxdb_free_result</span><span style="color: #007700">(</span><span style="color: #0000BB">$result</span><span style="color: #007700">);<br />}<br /><br /></span><span style="color: #FF8000">/* change db to non existing db */<br /></span><span style="color: #0000BB">maxdb_select_db</span><span style="color: #007700">(</span><span style="color: #0000BB">$link</span><span style="color: #007700">, </span><span style="color: #DD0000">"XXXXXXXX"</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/* return name of current default database */<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">$result </span><span style="color: #007700">= </span><span style="color: #0000BB">maxdb_query</span><span style="color: #007700">(</span><span style="color: #0000BB">$link</span><span style="color: #007700">, </span><span style="color: #DD0000">"SELECT SERVERDB FROM USERS WHERE USERNAME='MONA'"</span><span style="color: #007700">)) {<br /> </span><span style="color: #0000BB">$row </span><span style="color: #007700">= </span><span style="color: #0000BB">maxdb_fetch_row</span><span style="color: #007700">(</span><span style="color: #0000BB">$result</span><span style="color: #007700">);<br /> </span><span style="color: #0000BB">printf</span><span style="color: #007700">(</span><span style="color: #DD0000">"Default database is %s.\n"</span><span style="color: #007700">, </span><span style="color: #0000BB">$row</span><span style="color: #007700">[</span><span style="color: #0000BB">0</span><span style="color: #007700">]);<br /> </span><span style="color: #0000BB">maxdb_free_result</span><span style="color: #007700">(</span><span style="color: #0000BB">$result</span><span style="color: #007700">);<br />}<br /><br /></span><span style="color: #0000BB">maxdb_close</span><span style="color: #007700">(</span><span style="color: #0000BB">$link</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
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</span>
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</pre></div>
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</div>
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</div>
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<p class="para">以上例程的输出类似于：</p>
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<div class="example-contents screen">
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<div class="cdata"><pre>
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Default database is <...>.
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Warning: maxdb_select_db(): -10709 Connection failed (RTE:database not running) <...>
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Warning: maxdb_query(): -10821 Session not connected [] <...>
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Warning: maxdb_close(): -10821 Session not connected [] <...>
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</pre></div>
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</div>
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</div>
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<div class="refsect1 seealso" id="refsect1-function.maxdb-select-db-seealso">
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<h3 class="title">参见</h3>
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<p class="para">
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<ul class="simplelist">
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<li class="member"><span class="function"><a href="maxdb_connect.html" class="function" rel="rdfs-seeAlso">maxdb_connect()</a> - Open a new connection to the MaxDB server</span></li>
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<li class="member"><span class="function"><a href="maxdb_real_connect.html" class="function" rel="rdfs-seeAlso">maxdb_real_connect()</a> - Opens a connection to a MaxDB server</span></li>
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</ul>
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</p>
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</div>
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</div></div></div></body></html> |