You want to retrieve data from a database.
Use SELECT to retrieve data from a table based on some criteria. use SELECT * FROM to list all the fields and rows in a table.
SELECT column_name FROM table_name;
<!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>Retrieving Data from a Database</title>
<meta Name="Author" Content="Hann So">
</head>
<body>
<p>
<?php
if (isset($_POST['submit'])) {
process_form();
}
else {
display_form();// display form for the first time
}
function display_form() {
echo <<<HTML
<h2>Retrieving Data from a Database</h2>
<form action = "$_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 />
Database name:
<input type="text" name="db" size="50" value="hann_db" />
<br />
Table name:
<input type="text" name="table" size="50" value="blog_entries" />
<br />
Sort (DESC= descending, ASC=Ascending):
<input type="text" name="sort" size="50" value="date_entered DESC" />
<br />
<input type="submit" name="submit" value="Submit" />
</form>
HTML;
}
function process_form() {
DEFINE ('DB_HOST', "localhost");
DEFINE ('DB_USER', "$_POST[username]");
DEFINE ('DB_PASSWORD', "$_POST[password]");
DEFINE ('DB_NAME', "$_POST[db]");
DEFINE ('TABLE_NAME', "$_POST[table]");
$sort = stripslashes(trim($_POST[sort]));
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>";
// select a database
if (@mysql_select_db(DB_NAME)) {
echo "<P>The database ", DB_NAME, " has been selected.</p>";
}
else {
die ("<p>Could not select the database because: ". mysql_error(). "</p>");
}
// define the query
// every column of every row
// DESC = descending, ASC= ascending
$query = "SELECT * FROM " . TABLE_NAME . " ORDER BY " . "$sort";
// run the query
if ($r = @mysql_query($query)) {
// retrieve and print every record
echo "<h3>The table has the following entries:</h3>";
// mysql_fetch_array fetches a result row as an associative array,
// a numeric array, or both
while ($row = mysql_fetch_array($r)) {
echo "<p>blog_id={$row['blog_id']}<h4>{$row['title']}</h4>
{$row['entry']}<br />
<a href=\"example_u.php?id={$row['blog_id']}\">Edit</a>
<a href=\"example_d.php?id={$row['blog_id']}\">Delete</a>
</p><hr />";
}
// close the connection
mysql_close($link);
}
else {
die ("<p>Could not retrieve records because: ". mysql_error(). "</p>");
}
}
else {
die ("<p>Could not connect to MySQL because: ". mysql_error(). "</p>");
}
echo "<p><a href=\"$_SERVER[SCRIPT_NAME]\">Try again?</a></p>\n";
echo "<p><a href=\"example_i.php\">Insert data?</a></p>\n";
echo "<p><a href=\"example_u.php\">Update data?</a></p>\n";
echo "<p><a href=\"example_d.php\">Delete data?</a></p>\n";
}
?>
</p>
</body>
</html>
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