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<h1 class="refname">mysqli::__construct</h1>
<h1 class="refname">mysqli_connect</h1>
<p class="verinfo">(PHP 5)</p><p class="refpurpose"><span class="refname">mysqli::__construct</span> -- <span class="refname">mysqli_connect</span> — <span class="dc-title">Open a new connection to the MySQL server</span></p>
</div>
<div class="refsect1 description" id="refsect1-mysqli.construct-description">
<h3 class="title">Description</h3>
<p class="para">Object oriented style</p>
<div class="constructorsynopsis dc-description">
<span class="methodname"><strong>mysqli::__construct()</strong></span>
([ <span class="methodparam"><span class="type">string</span> <code class="parameter">$host</code><span class="initializer"> = ini_get("mysqli.default_host")</span></span>
[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$username</code><span class="initializer"> = ini_get("mysqli.default_user")</span></span>
[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$passwd</code><span class="initializer"> = ini_get("mysqli.default_pw")</span></span>
[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$dbname</code><span class="initializer"> = ""</span></span>
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$port</code><span class="initializer"> = ini_get("mysqli.default_port")</span></span>
[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$socket</code><span class="initializer"> = ini_get("mysqli.default_socket")</span></span>
]]]]]] )</div>
<p class="para rdfs-comment">Procedural style</p>
<div class="methodsynopsis dc-description">
<span class="type"><a href="class.mysqli.html" class="type mysqli">mysqli</a></span> <span class="methodname"><a href="function.mysqli-connect.html" class="methodname">mysqli_connect</a></span>
([ <span class="methodparam"><span class="type">string</span> <code class="parameter">$host</code><span class="initializer"> = ini_get("mysqli.default_host")</span></span>
[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$username</code><span class="initializer"> = ini_get("mysqli.default_user")</span></span>
[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$passwd</code><span class="initializer"> = ini_get("mysqli.default_pw")</span></span>
[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$dbname</code><span class="initializer"> = ""</span></span>
[, <span class="methodparam"><span class="type">int</span> <code class="parameter">$port</code><span class="initializer"> = ini_get("mysqli.default_port")</span></span>
[, <span class="methodparam"><span class="type">string</span> <code class="parameter">$socket</code><span class="initializer"> = ini_get("mysqli.default_socket")</span></span>
]]]]]] )</div>
<p class="para rdfs-comment">
Opens a connection to the MySQL Server running on.
</p>
</div>
<div class="refsect1 parameters" id="refsect1-mysqli.construct-parameters">
<h3 class="title">Parameters</h3>
<p class="para">
<dl>
<dt>
<span class="term"><em><code class="parameter">host</code></em></span>
<dd>
<p class="para">
Can be either a host name or an IP address. Passing the <strong><code>NULL</code></strong> value
or the string "localhost" to this parameter, the local host is
assumed. When possible, pipes will be used instead of the TCP/IP
protocol.
</p>
<p class="para">
Prepending host by <em>p:</em> opens a persistent connection.
<span class="function"><a href="mysqli.change-user.html" class="function">mysqli_change_user()</a></span> is automatically called on
connections opened from the connection pool.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">username</code></em></span>
<dd>
<p class="para">
The MySQL user name.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">passwd</code></em></span>
<dd>
<p class="para">
If not provided or <strong><code>NULL</code></strong>, the MySQL server will attempt to authenticate
the user against those user records which have no password only. This
allows one username to be used with different permissions (depending
on if a password as provided or not).
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">dbname</code></em></span>
<dd>
<p class="para">
If provided will specify the default database to be used when
performing queries.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">port</code></em></span>
<dd>
<p class="para">
Specifies the port number to attempt to connect to the MySQL server.
</p>
</dd>
</dt>
<dt>
<span class="term"><em><code class="parameter">socket</code></em></span>
<dd>
<p class="para">
Specifies the socket or named pipe that should be used.
</p>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Specifying the <em><code class="parameter">socket</code></em> parameter will not
explicitly determine the type of connection to be used when
connecting to the MySQL server. How the connection is made to the
MySQL database is determined by the <em><code class="parameter">host</code></em>
parameter.
</p>
</p></blockquote>
</dd>
</dt>
</dl>
</p>
</div>
<div class="refsect1 returnvalues" id="refsect1-mysqli.construct-returnvalues">
<h3 class="title">Return Values</h3>
<p class="para">
Returns an object which represents the connection to a MySQL Server.
</p>
</div>
<div class="refsect1 changelog" id="refsect1-mysqli.construct-changelog">
<h3 class="title">Changelog</h3>
<p class="para">
<table class="doctable informaltable">
<thead>
<tr>
<th>Version</th>
<th>Description</th>
</tr>
</thead>
<tbody class="tbody">
<tr>
<td>5.3.0</td>
<td>
Added the ability of persistent connections.
</td>
</tr>
</tbody>
</table>
</p>
</div>
<div class="refsect1 examples" id="refsect1-mysqli.construct-examples">
<h3 class="title">Examples</h3>
<div class="example" id="example-1656">
<p><strong>Example #1 <span class="methodname"><strong>mysqli::__construct()</strong></span> example</strong></p>
<div class="example-contents"><p>Object oriented style</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$mysqli </span><span style="color: #007700">= new </span><span style="color: #0000BB">mysqli</span><span style="color: #007700">(</span><span style="color: #DD0000">'localhost'</span><span style="color: #007700">, </span><span style="color: #DD0000">'my_user'</span><span style="color: #007700">, </span><span style="color: #DD0000">'my_password'</span><span style="color: #007700">, </span><span style="color: #DD0000">'my_db'</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">/*<br /> * This is the "official" OO way to do it,<br /> * BUT $connect_error was broken until PHP 5.2.9 and 5.3.0.<br /> */<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">connect_error</span><span style="color: #007700">) {<br /> die(</span><span style="color: #DD0000">'Connect Error (' </span><span style="color: #007700">. </span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">connect_errno </span><span style="color: #007700">. </span><span style="color: #DD0000">') '<br /> </span><span style="color: #007700">. </span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">connect_error</span><span style="color: #007700">);<br />}<br /><br /></span><span style="color: #FF8000">/*<br /> * Use this instead of $connect_error if you need to ensure<br /> * compatibility with PHP versions prior to 5.2.9 and 5.3.0.<br /> */<br /></span><span style="color: #007700">if (</span><span style="color: #0000BB">mysqli_connect_error</span><span style="color: #007700">()) {<br /> die(</span><span style="color: #DD0000">'Connect Error (' </span><span style="color: #007700">. </span><span style="color: #0000BB">mysqli_connect_errno</span><span style="color: #007700">() . </span><span style="color: #DD0000">') '<br /> </span><span style="color: #007700">. </span><span style="color: #0000BB">mysqli_connect_error</span><span style="color: #007700">());<br />}<br /><br />echo </span><span style="color: #DD0000">'Success... ' </span><span style="color: #007700">. </span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">host_info </span><span style="color: #007700">. </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">$mysqli</span><span style="color: #007700">-></span><span style="color: #0000BB">close</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>Object oriented style when extending mysqli class</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br /><br /></span><span style="color: #007700">class </span><span style="color: #0000BB">foo_mysqli </span><span style="color: #007700">extends </span><span style="color: #0000BB">mysqli </span><span style="color: #007700">{<br /> public function </span><span style="color: #0000BB">__construct</span><span style="color: #007700">(</span><span style="color: #0000BB">$host</span><span style="color: #007700">, </span><span style="color: #0000BB">$user</span><span style="color: #007700">, </span><span style="color: #0000BB">$pass</span><span style="color: #007700">, </span><span style="color: #0000BB">$db</span><span style="color: #007700">) {<br /> </span><span style="color: #0000BB">parent</span><span style="color: #007700">::</span><span style="color: #0000BB">__construct</span><span style="color: #007700">(</span><span style="color: #0000BB">$host</span><span style="color: #007700">, </span><span style="color: #0000BB">$user</span><span style="color: #007700">, </span><span style="color: #0000BB">$pass</span><span style="color: #007700">, </span><span style="color: #0000BB">$db</span><span style="color: #007700">);<br /><br /> if (</span><span style="color: #0000BB">mysqli_connect_error</span><span style="color: #007700">()) {<br /> die(</span><span style="color: #DD0000">'Connect Error (' </span><span style="color: #007700">. </span><span style="color: #0000BB">mysqli_connect_errno</span><span style="color: #007700">() . </span><span style="color: #DD0000">') '<br /> </span><span style="color: #007700">. </span><span style="color: #0000BB">mysqli_connect_error</span><span style="color: #007700">());<br /> }<br /> }<br />}<br /><br /></span><span style="color: #0000BB">$db </span><span style="color: #007700">= new </span><span style="color: #0000BB">foo_mysqli</span><span style="color: #007700">(</span><span style="color: #DD0000">'localhost'</span><span style="color: #007700">, </span><span style="color: #DD0000">'my_user'</span><span style="color: #007700">, </span><span style="color: #DD0000">'my_password'</span><span style="color: #007700">, </span><span style="color: #DD0000">'my_db'</span><span style="color: #007700">);<br /><br />echo </span><span style="color: #DD0000">'Success... ' </span><span style="color: #007700">. </span><span style="color: #0000BB">$db</span><span style="color: #007700">-></span><span style="color: #0000BB">host_info </span><span style="color: #007700">. </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">$db</span><span style="color: #007700">-></span><span style="color: #0000BB">close</span><span style="color: #007700">();<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>Procedural style</p></div>
<div class="example-contents">
<div class="phpcode"><code><span style="color: #000000">
<span style="color: #0000BB"><?php<br />$link </span><span style="color: #007700">= </span><span style="color: #0000BB">mysqli_connect</span><span style="color: #007700">(</span><span style="color: #DD0000">'localhost'</span><span style="color: #007700">, </span><span style="color: #DD0000">'my_user'</span><span style="color: #007700">, </span><span style="color: #DD0000">'my_password'</span><span style="color: #007700">, </span><span style="color: #DD0000">'my_db'</span><span style="color: #007700">);<br /><br />if (!</span><span style="color: #0000BB">$link</span><span style="color: #007700">) {<br /> die(</span><span style="color: #DD0000">'Connect Error (' </span><span style="color: #007700">. </span><span style="color: #0000BB">mysqli_connect_errno</span><span style="color: #007700">() . </span><span style="color: #DD0000">') '<br /> </span><span style="color: #007700">. </span><span style="color: #0000BB">mysqli_connect_error</span><span style="color: #007700">());<br />}<br /><br />echo </span><span style="color: #DD0000">'Success... ' </span><span style="color: #007700">. </span><span style="color: #0000BB">mysqli_get_host_info</span><span style="color: #007700">(</span><span style="color: #0000BB">$link</span><span style="color: #007700">) . </span><span style="color: #DD0000">"\n"</span><span style="color: #007700">;<br /><br /></span><span style="color: #0000BB">mysqli_close</span><span style="color: #007700">(</span><span style="color: #0000BB">$link</span><span style="color: #007700">);<br /></span><span style="color: #0000BB">?></span>
</span>
</code></div>
</div>
<div class="example-contents"><p>The above examples will output:</p></div>
<div class="example-contents screen">
<div class="cdata"><pre>
Success... MySQL host info: localhost via TCP/IP
</pre></div>
</div>
</div>
</div>
<div class="refsect1 notes" id="refsect1-mysqli.construct-notes">
<h3 class="title">Notes</h3>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">MySQLnd always assumes the server default charset. This charset is sent during connection
hand-shake/authentication, which mysqlnd will use.</p><p class="para">Libmysqlclient uses the default charset set in the
<var class="filename">my.cnf</var> or by an explicit call to <span class="function"><a href="mysqli.options.html" class="function">mysqli_options()</a></span> prior to
calling <span class="function"><a href="mysqli.real-connect.html" class="function">mysqli_real_connect()</a></span>, but after <span class="function"><a href="mysqli.init.html" class="function">mysqli_init()</a></span>.</p></p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
OO syntax only: If a connection fails an object is still returned. To check
if the connection failed then use either the
<span class="function"><a href="mysqli.connect-error.html" class="function">mysqli_connect_error()</a></span> function or the <a href="mysqli.connect-error.html" class="link">mysqli->connect_error</a> property as in
the preceding examples.
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
If it is necessary to set options, such as the connection timeout,
<span class="function"><a href="mysqli.real-connect.html" class="function">mysqli_real_connect()</a></span> must be used instead.
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Calling the constructor with no parameters is the same as calling
<span class="function"><a href="mysqli.init.html" class="function">mysqli_init()</a></span>.
</p>
</p></blockquote>
<blockquote class="note"><p><strong class="note">Note</strong>:
<p class="para">
Error "Can't create TCP/IP socket (10106)" usually means that the <a href="ini.core.html#ini.variables-order" class="link">variables_order</a> configure directive
doesn't contain character <em>E</em>. On Windows, if the
environment is not copied the <em>SYSTEMROOT</em> environment
variable won't be available and PHP will have problems loading Winsock.
</p>
</p></blockquote>
</div>
<div class="refsect1 seealso" id="refsect1-mysqli.construct-seealso">
<h3 class="title">See Also</h3>
<p class="para">
<ul class="simplelist">
<li class="member"> <span class="function"><a href="mysqli.real-connect.html" class="function" rel="rdfs-seeAlso">mysqli_real_connect()</a> - Opens a connection to a mysql server</span></li>
<li class="member"> <span class="function"><a href="mysqli.options.html" class="function" rel="rdfs-seeAlso">mysqli_options()</a> - Set options</span></li>
<li class="member"> <span class="function"><a href="mysqli.connect-errno.html" class="function" rel="rdfs-seeAlso">mysqli_connect_errno()</a> - Returns the error code from last connect call</span></li>
<li class="member"> <span class="function"><a href="mysqli.connect-error.html" class="function" rel="rdfs-seeAlso">mysqli_connect_error()</a> - Returns a string description of the last connect error</span></li>
<li class="member"> <span class="function"><a href="mysqli.close.html" class="function" rel="rdfs-seeAlso">mysqli_close()</a> - Closes a previously opened database connection</span></li>
</ul>
</p>
</div>
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