mysql-connect.xml

<?xml version="1.0" encoding="utf-8"?>
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<refentry xml:id="function.mysql-connect" xmlns="http://docbook.org/ns/docbook">
 <refnamediv>
  <refname>mysql_connect</refname>
  <refpurpose>打开一个到 MySQL 服务器的连接</refpurpose>
 </refnamediv>

 <refsynopsisdiv>
  <warning>
   &mysql.alternative.note;
   <simplelist role="alternatives">
    <member><function>mysqli_connect</function></member>
    <member><methodname>PDO::__construct</methodname></member>
   </simplelist>
  </warning>
 </refsynopsisdiv>

 <refsect1 role="description">
  &reftitle.description;
  <methodsynopsis>
   <type class="union"><type>resource</type><type>false</type></type><methodname>mysql_connect</methodname>
   <methodparam choice="opt"><type>string</type><parameter>server</parameter><initializer>ini_get("mysql.default_host")</initializer></methodparam>
   <methodparam choice="opt"><type>string</type><parameter>username</parameter><initializer>ini_get("mysql.default_user")</initializer></methodparam>
   <methodparam choice="opt"><type>string</type><parameter>password</parameter><initializer>ini_get("mysql.default_password")</initializer></methodparam>
   <methodparam choice="opt"><type>bool</type><parameter>new_link</parameter><initializer>&false;</initializer></methodparam>
   <methodparam choice="opt"><type>int</type><parameter>client_flags</parameter><initializer>0</initializer></methodparam>
  </methodsynopsis>
  <para>
   打开或重复使用一个到 MySQL 服务器的连接。
  </para>
 </refsect1>

 <refsect1 role="parameters">
  &reftitle.parameters;
  <para>
   <variablelist>
    <varlistentry>
     <term><parameter>server</parameter></term>
     <listitem>
      <para>
       MySQL 服务器。可以包括端口号，例如
       "hostname:port"，或者到本地套接字的路径，例如对于 localhost 的 ":/path/to/socket"。
      </para>
      <para>
       如果 PHP 指令 <link linkend="ini.mysql.default-host">
       mysql.default_host</link> 未定义（默认情况），则默认值是 'localhost:3306'。
       在 &sqlsafemode; 时，参数被忽略，总是使用 'localhost:3306'。
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>username</parameter></term>
     <listitem>
      <para>
       用户名。默认值由 <link
       linkend="ini.mysql.default-user">mysql.default_user</link> 定义。 在
       &sqlsafemode; 时，参数被忽略，总是使用服务器进程所有者的用户名。
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>password</parameter></term>
     <listitem>
      <para>
       密码。默认值由<link
       linkend="ini.mysql.default-password">mysql.default_password</link>定义。在
       &sqlsafemode; 时，参数被忽略，总是使用空密码。
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>new_link</parameter></term>
     <listitem>
      <para>
       如果用同样的参数第二次调用
       <function>mysql_connect</function>，将不会建立新连接，而将返回已经打开的连接标识。参数
       <parameter>new_link</parameter> 改变此行为并使
       <function>mysql_connect</function> 总是打开新的连接，甚至当
       <function>mysql_connect</function> 曾在前面被用同样的参数调用过。
      </para>
     </listitem>
    </varlistentry>
    <varlistentry>
     <term><parameter>client_flags</parameter></term>
     <listitem>
      <para>
       <parameter>client_flags</parameter>
       参数可以是以下常量的组合：<constant>MYSQL_CLIENT_SSL</constant>，<constant>MYSQL_CLIENT_COMPRESS</constant>，<constant>MYSQL_CLIENT_IGNORE_SPACE</constant>
       或 <constant>MYSQL_CLIENT_INTERACTIVE</constant>。进一步信息见
       <xref linkend="mysql.client-flags" />。
      </para>
     </listitem>
    </varlistentry>
   </variablelist>
  </para>
 </refsect1>

 <refsect1 role="returnvalues">
  &reftitle.returnvalues;
  <para>
   如果成功则返回一个 MySQL 连接标识，&return.falseforfailure;。
  </para>
 </refsect1>

 <refsect1 role="examples">
  &reftitle.examples;
  <para>
   <example>
    <title><function>mysql_connect</function> 示例</title>
    <programlisting role="php">
<![CDATA[
<?php
$link = mysql_connect('localhost', 'mysql_user', 'mysql_password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
mysql_close($link);
?>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   <example>
    <title><function>mysql_connect</function> 示例：使用 <literal>hostname:port</literal> 语法</title>
    <programlisting role="php">
<![CDATA[
<?php
// we connect to example.com and port 3307
$link = mysql_connect('example.com:3307', 'mysql_user', 'mysql_password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
mysql_close($link);

// we connect to localhost at port 3307
$link = mysql_connect('127.0.0.1:3307', 'mysql_user', 'mysql_password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
mysql_close($link);
?>
]]>
    </programlisting>
   </example>
  </para>
  <para>
   <example>
    <title><function>mysql_connect</function> 示例：使用 ":/path/to/socket" 语法</title>
    <programlisting role="php">
<![CDATA[
<?php
// we connect to localhost and socket e.g. /tmp/mysql.sock

// variant 1: omit localhost
$link = mysql_connect(':/tmp/mysql', 'mysql_user', 'mysql_password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
mysql_close($link);


// variant 2: with localhost
$link = mysql_connect('localhost:/tmp/mysql.sock', 'mysql_user', 'mysql_password');
if (!$link) {
    die('Could not connect: ' . mysql_error());
}
echo 'Connected successfully';
mysql_close($link);
?>
]]>
    </programlisting>
   </example>
  </para>
 </refsect1>

 <refsect1 role="notes">
  &reftitle.notes;
  <note>
   <para>
    只要将 server 指定为 &quot;localhost&quot; 或
    &quot;localhost:port&quot;，MySQL 客户端库会越过此值并尝试连接到本地套接字（Windows
    中的名字管道）。如果想用 TCP/IP，应该用 &quot;127.0.0.1&quot;
    代替 &quot;localhost&quot;。如果 MySQL 客户端库试图连接到一个错误的本地套接字，则应该在
    &php.ini; 中设置 <link linkend="ini.mysql.default-host">mysql.default_host</link>
    的正确路径并把 server 留空。
   </para>
  </note>
  <note>
   <para>
    脚本一结束，到服务器的连接就被关闭，除非之前已经明确调用
    <function>mysql_close</function> 关闭了。
   </para>
  </note>
  <note>
   <para>
    Error "Can't create TCP/IP socket (10106)" usually means that the <link
    linkend="ini.variables-order">variables_order</link> configure directive
    doesn't contain character <literal>E</literal>. On Windows, if the
    environment is not copied the <literal>SYSTEMROOT</literal> environment
    variable won't be available and PHP will have problems loading Winsock.
   </para>
  </note>
 </refsect1>

 <refsect1 role="seealso">
  &reftitle.seealso;
  <para>
   <simplelist>
    <member><function>mysql_pconnect</function></member>
    <member><function>mysql_close</function></member>
   </simplelist>
  </para>
 </refsect1>
</refentry>

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