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?>
<div id="pdo.connect" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">PDO::connect</h1>
  <p class="verinfo">(PHP 8 &gt;= 8.4.0)</p><p class="refpurpose"><span class="refname">PDO::connect</span> &mdash; <span class="dc-title">Connect to a database and return a PDO subclass for drivers that support it</span></p>

 </div>

 <div class="refsect1 description" id="refsect1-pdo.connect-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="modifier">public</span> <span class="modifier">static</span> <span class="methodname"><strong>PDO::connect</strong></span>(<br>&nbsp;&nbsp;&nbsp;&nbsp;<span class="methodparam"><span class="type"><a href="language.types.string.php" class="type string">string</a></span> <code class="parameter">$dsn</code></span>,<br>&nbsp;&nbsp;&nbsp;&nbsp;<span class="methodparam"><span class="type"><span class="type"><a href="language.types.null.php" class="type null">?</a></span><span class="type"><a href="language.types.string.php" class="type string">string</a></span></span> <code class="parameter">$username</code><span class="initializer"> = <strong><code><a href="reserved.constants.php#constant.null">null</a></code></strong></span></span>,<br>&nbsp;&nbsp;&nbsp;&nbsp;<span class="methodparam"><span class="attribute"><a href="class.sensitiveparameter.php">#[\SensitiveParameter]</a> </span><span class="type"><span class="type"><a href="language.types.null.php" class="type null">?</a></span><span class="type"><a href="language.types.string.php" class="type string">string</a></span></span> <code class="parameter">$password</code><span class="initializer"> = <strong><code><a href="reserved.constants.php#constant.null">null</a></code></strong></span></span>,<br>&nbsp;&nbsp;&nbsp;&nbsp;<span class="methodparam"><span class="type"><span class="type"><a href="language.types.null.php" class="type null">?</a></span><span class="type"><a href="language.types.array.php" class="type array">array</a></span></span> <code class="parameter">$options</code><span class="initializer"> = <strong><code><a href="reserved.constants.php#constant.null">null</a></code></strong></span></span><br>): <span class="type">static</span></div>

  <p class="simpara">
   Creates an instance of a <span class="classname"><a href="class.pdo.php" class="classname">PDO</a></span> subclass for the
   database being connection if it exists,
   otherwise return a generic <span class="classname"><a href="class.pdo.php" class="classname">PDO</a></span> instance.
  </p>
 </div>


 <div class="refsect1 parameters" id="refsect1-pdo.connect-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>
    
     <dt><code class="parameter">dsn</code></dt>
     <dd>
      <p class="para">
       数据源名称或叫做 DSN，包含了请求连接到数据库的信息。
      </p>
      <p class="para">
       通常，一个 DSN 由 PDO 驱动名、紧随其后的冒号、以及具体 PDO 驱动的连接语法组成。更深入的信息能从 <a href="pdo.drivers.php" class="link">PDO 具体驱动文档</a>找到。
      </p>
      <p class="para">
       <code class="parameter">dsn</code> 参数支持三种不同的方式 创建一个数据库连接：
      </p>
      <p class="para">
       <dl>
        <dt>驱动程序调用</dt>
         <dd>
          <p class="para">
           <code class="parameter">dsn</code> 包含完整的DSN。
          </p>
         </dd>
        
        <dt>URI 调用</dt>
         <dd>
          <p class="para">
           <code class="parameter">dsn</code> 由 <strong class="userinput"><code>uri:</code></strong> 后跟 URI 组成，该 URI 包含定义 DSN
           字符串的文件位置。URI 可以指定本地文件或远程 URL。
          </p>
          <p class="para"><strong class="userinput"><code>uri:file:///path/to/dsnfile</code></strong></p>
         </dd>
        
        <dt>别名</dt>
         <dd>
          <p class="para">
           <code class="parameter">dsn</code> 由映射到 <var class="filename">php.ini</var> 中定义 DSN 字符串的 <code class="code">pdo.dsn.<code class="parameter">name</code></code>
           的 <code class="parameter">name</code> 名组成。
          </p>
          <blockquote class="note"><p><strong class="note">注意</strong>: 
           <p class="para">
             别名必须得在 <var class="filename">php.ini</var> 中定义了，不能是在 <var class="filename">.htaccess</var> 或 <var class="filename">httpd.conf</var> 中 。
           </p>
          </p></blockquote>
         </dd>
        
       </dl>
      </p>
     </dd>
    
    
     <dt><code class="parameter">username</code></dt>
     <dd>
      <p class="para">
       DSN字符串中的用户名。对于某些PDO驱动，此参数为可选项。
      </p>
     </dd>
    
    
     <dt><code class="parameter">password</code></dt>
     <dd>
      <p class="para">
       DSN字符串中的密码。对于某些PDO驱动，此参数为可选项。
      </p>
     </dd>
    
    
     <dt><code class="parameter">options</code></dt>
     <dd>
      <p class="para">
       一个具体驱动的连接选项的键=&gt;值数组。
      </p>
     </dd>
    
   </dl>
  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-pdo.connect-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="simpara">
   Returns an instance of a <span class="classname"><a href="class.pdo.php" class="classname">PDO</a></span> subclass for the
   corresponding PDO driver if it exists,
   or a generic <span class="classname"><a href="class.pdo.php" class="classname">PDO</a></span> instance.
  </p>
 </div>


 <div class="refsect1 errors" id="refsect1-pdo.connect-errors">
  <h3 class="title">错误／异常</h3>
  <p class="para">
   如果试图连接到请求的数据库失败，无论当前设置了哪个 <strong><code><a href="pdo.constants.php#pdo.constants.attr-errmode">PDO::ATTR_ERRMODE</a></code></strong>，则会抛出 <span class="classname"><a href="class.pdoexception.php" class="classname">PDOException</a></span>。
  </p>
 </div>


 <div class="refsect1 seealso" id="refsect1-pdo.connect-seealso">
  <h3 class="title">参见</h3>
  <ul class="simplelist">
   <li><span class="classname"><a href="class.pdo-dblib.php" class="classname">Pdo\Dblib</a></span></li>
   <li><span class="classname"><a href="class.pdo-firebird.php" class="classname">Pdo\Firebird</a></span></li>
   <li><span class="classname"><a href="class.pdo-mysql.php" class="classname">Pdo\Mysql</a></span></li>
   <li><span class="classname"><a href="class.pdo-odbc.php" class="classname">Pdo\Odbc</a></span></li>
   <li><span class="classname"><a href="class.pdo-pgsql.php" class="classname">Pdo\Pgsql</a></span></li>
   <li><span class="classname"><a href="class.pdo-sqlite.php" class="classname">Pdo\Sqlite</a></span></li>
   <li><span class="methodname"><a href="pdo.construct.php" class="methodname" rel="rdfs-seeAlso">PDO::__construct()</a> - 创建一个表示数据库连接的 PDO 实例</span></li>
  </ul>
 </div>


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