Before you can use a database, you need to connect to the database server MySQL first. This connection is used as the access point for any future commands.
Use mysql_connect('localhost', 'username', 'password'). It returns a connection if successful. If not it returns False. The localhost value is used as the host name when both the PHP script and the MySQL database reside on the same computer.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="EN" lang="EN">
<head>
<title>Connect to MySQL</title>
<meta Name="Author" Content="Hann So">
</head>
<body>
<p>
<?php
if (isset($_POST['submit'])) {
process_form();
}
else {
display_form();// display form for the first time
}
function display_form() {
echo <<<HTML
<h2>Connect to MySQL</h2>
<form action = "$_SERVER[SCRIPT_NAME]" method="post">
Username:
<input type="text" name="username" size="50" value="hann" />
<br />
Password:
<input type="password" name="password" size="50" />
<br />
<input type="submit" name="submit" value="Submit" />
</form>
HTML;
}
function process_form() {
DEFINE ('DB_USER', "$_POST[username]");
DEFINE ('DB_PASSWORD', "$_POST[password]");
DEFINE ('DB_HOST', "localhost");
echo "<p>Opening the connection to the database server.</p>";
if ($link = mysql_connect(DB_HOST, DB_USER, DB_PASSWORD)) {
echo "<p>The connection worked. The link is $link</p>";
mysql_close($link);
}
else {
echo "<p>Could not connect to MySQL.</p>";
}
echo "<p><a href=\"$_SERVER[SCRIPT_NAME]\">Try again?</a></p>\n";
}
?>
</p>
</body>
</html>
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