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?>
<div id="function.pg-connect" class="refentry">
 <div class="refnamediv">
  <h1 class="refname">pg_connect</h1>
  <p class="verinfo">(PHP 4, PHP 5, PHP 7, PHP 8)</p><p class="refpurpose"><span class="refname">pg_connect</span> &mdash; <span class="dc-title">打开 PostgreSQL 连接</span></p>

 </div>

 <div class="refsect1 description" id="refsect1-function.pg-connect-description">
  <h3 class="title">说明</h3>
  <div class="methodsynopsis dc-description">
   <span class="methodname"><strong>pg_connect</strong></span>(<span class="methodparam"><span class="type"><a href="language.types.string.php" class="type string">string</a></span> <code class="parameter">$connection_string</code></span>, <span class="methodparam"><span class="type"><a href="language.types.integer.php" class="type int">int</a></span> <code class="parameter">$flags</code><span class="initializer"> = 0</span></span>): <span class="type"><span class="type"><a href="class.pgsql-connection.php" class="type PgSql\Connection">PgSql\Connection</a></span>|<span class="type"><a href="language.types.singleton.php" class="type false">false</a></span></span></div>

  <p class="para rdfs-comment">
   <span class="function"><strong>pg_connect()</strong></span> 打开通过 <code class="parameter">connection_string</code> 指定的 PostgreSQL 数据库的连接。
  </p>
  <p class="para">
   如果使用与现有连接相同的 <code class="parameter">connection_string</code> 对 <span class="function"><strong>pg_connect()</strong></span>
   进行第二次调用，将返回现有连接，除非将 <strong><code><a href="pgsql.constants.php#constant.pgsql-connect-force-new">PGSQL_CONNECT_FORCE_NEW</a></code></strong> 作为
   <code class="parameter">flags</code> 传递。
  </p>
  <p class="para">
   弃用有多个参数的旧语法 <strong class="command">$conn = pg_connect(&quot;host&quot;, &quot;port&quot;, &quot;options&quot;, &quot;tty&quot;, &quot;dbname&quot;)</strong>。
  </p>
 </div>


<div class="refsect1 parameters" id="refsect1-function.pg-connect-parameters">
  <h3 class="title">参数</h3>
  <p class="para">
   <dl>
    
     <dt><code class="parameter">connection_string</code></dt>
     <dd>
      <p class="para">
       <code class="parameter">connection_string</code> 可以为空以使用所有默认参数，或者可以包含一个或多个由空格分隔的参数设置。
       每个参数设置的形式为 <code class="literal">keyword = value</code>。等号两旁的空格是可选的。写入空值或包含空格的值，请用单引号将其括起来，例如
       <code class="literal">keyword = &#039;a value&#039;</code>。值中的单引号和反斜线必须使用反斜线转义，即 \&#039; 和 \\。
      </p>
      <p class="para">
       当前可识别的参数关键字有
       <code class="parameter">host</code>、<code class="parameter">hostaddr</code>、<code class="parameter">port</code>、<code class="parameter">dbname</code>（默认为
       <code class="parameter">user</code> 的值）、<code class="parameter">user</code>、<code class="parameter">password</code>、<code class="parameter">connect_timeout</code>、<code class="parameter">options</code>、<code class="parameter">tty</code>（忽略）、<code class="parameter">sslmode</code>、<code class="parameter">requiressl</code>（弃用
       <code class="parameter">sslmode</code>）和 <code class="parameter">service</code>。存在哪些参数取决于 PostgreSQL 版本。
      </p>
      <p class="para">
       The <code class="parameter">options</code> parameter can be used to set command line parameters 
       to be invoked by the server.
      </p>
     </dd>
    
    
     <dt><code class="parameter">flags</code></dt>
     <dd>
      <p class="para">
       如果传递 <strong><code><a href="pgsql.constants.php#constant.pgsql-connect-force-new">PGSQL_CONNECT_FORCE_NEW</a></code></strong>，将会创建新连接，即使 <code class="parameter">connection_string</code>
       与现有连接相同。
      </p>
      <p class="para">
       如果指定 <strong><code><a href="pgsql.constants.php#constant.pgsql-connect-async">PGSQL_CONNECT_ASYNC</a></code></strong>，然后连接是异步创建。连接状态可以通过
       <span class="function"><a href="function.pg-connect-poll.php" class="function">pg_connect_poll()</a></span> 或 <span class="function"><a href="function.pg-connection-status.php" class="function">pg_connection_status()</a></span> 检测。
      </p>
     </dd>
    
   </dl>
  </p>
 </div>


 <div class="refsect1 returnvalues" id="refsect1-function.pg-connect-returnvalues">
  <h3 class="title">返回值</h3>
  <p class="para">
   成功时返回 <span class="classname"><a href="class.pgsql-connection.php" class="classname">PgSql\Connection</a></span> 实例， 或者在失败时返回 <strong><code><a href="reserved.constants.php#constant.false">false</a></code></strong>。
  </p>
 </div>


 <div class="refsect1 changelog" id="refsect1-function.pg-connect-changelog">
  <h3 class="title">更新日志</h3>
  <table class="doctable informaltable">
   
    <thead>
     <tr>
      <th>版本</th>
      <th>说明</th>
     </tr>

    </thead>

    <tbody class="tbody">
     <tr>
      <td>8.1.0</td>
      <td>
       现在返回 <span class="classname"><a href="class.pgsql-connection.php" class="classname">PgSql\Connection</a></span> 实例；之前返回 <span class="type"><a href="language.types.resource.php" class="type resource">resource</a></span>。
      </td>
     </tr>

    </tbody>
   
  </table>

 </div>


 <div class="refsect1 examples" id="refsect1-function.pg-connect-examples">
  <h3 class="title">示例</h3>
  <p class="para">
   <div class="example" id="example-1">
    <p><strong>示例 #1 使用 <span class="function"><strong>pg_connect()</strong></span></strong></p>
    <div class="example-contents">
<div class="phpcode"><code><span style="color: #000000"><span style="color: #0000BB">&lt;?php<br />$dbconn </span><span style="color: #007700">= </span><span style="color: #0000BB">pg_connect</span><span style="color: #007700">(</span><span style="color: #DD0000">"dbname=mary"</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">//connect to a database named "mary"<br /><br /></span><span style="color: #0000BB">$dbconn2 </span><span style="color: #007700">= </span><span style="color: #0000BB">pg_connect</span><span style="color: #007700">(</span><span style="color: #DD0000">"host=localhost port=5432 dbname=mary"</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">// connect to a database named "mary" on "localhost" at port "5432"<br /><br /></span><span style="color: #0000BB">$dbconn3 </span><span style="color: #007700">= </span><span style="color: #0000BB">pg_connect</span><span style="color: #007700">(</span><span style="color: #DD0000">"host=sheep port=5432 dbname=mary user=lamb password=foo"</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">//connect to a database named "mary" on the host "sheep" with a username and password<br /><br /></span><span style="color: #0000BB">$conn_string </span><span style="color: #007700">= </span><span style="color: #DD0000">"host=sheep port=5432 dbname=test user=lamb password=bar"</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">$dbconn4 </span><span style="color: #007700">= </span><span style="color: #0000BB">pg_connect</span><span style="color: #007700">(</span><span style="color: #0000BB">$conn_string</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">//connect to a database named "test" on the host "sheep" with a username and password<br /><br /></span><span style="color: #0000BB">$dbconn5 </span><span style="color: #007700">= </span><span style="color: #0000BB">pg_connect</span><span style="color: #007700">(</span><span style="color: #DD0000">"host=localhost options='--client_encoding=UTF8'"</span><span style="color: #007700">);<br /></span><span style="color: #FF8000">//connect to a database on "localhost" and set the command line parameter which tells the encoding is in UTF-8<br /></span><span style="color: #0000BB">?&gt;</span></span></code></div>
    </div>

   </div>
  </p>
 </div>


 <div class="refsect1 seealso" id="refsect1-function.pg-connect-seealso">
  <h3 class="title">参见</h3>
  <p class="para">
   <ul class="simplelist">
    <li><span class="function"><a href="function.pg-pconnect.php" class="function" rel="rdfs-seeAlso">pg_pconnect()</a> - 打开一个持久的 PostgreSQL 连接</span></li>
    <li><span class="function"><a href="function.pg-close.php" class="function" rel="rdfs-seeAlso">pg_close()</a> - 关闭 PostgreSQL 连接</span></li>
    <li><span class="function"><a href="function.pg-host.php" class="function" rel="rdfs-seeAlso">pg_host()</a> - 返回和某连接关联的主机名</span></li>
    <li><span class="function"><a href="function.pg-port.php" class="function" rel="rdfs-seeAlso">pg_port()</a> - 返回 connection 相关的端口号</span></li>
    <li><span class="function"><a href="function.pg-tty.php" class="function" rel="rdfs-seeAlso">pg_tty()</a> - 返回跟连接相关的 tty 名</span></li>
    <li><span class="function"><a href="function.pg-options.php" class="function" rel="rdfs-seeAlso">pg_options()</a> - 获得和 connection 相关的选项</span></li>
    <li><span class="function"><a href="function.pg-dbname.php" class="function" rel="rdfs-seeAlso">pg_dbname()</a> - 获取数据库名称</span></li>
   </ul>
  </p>
 </div>

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