PHP

Deleting Data in a Database
You want to delete data in a database.
use ,b>DELETE to delete rows in a table and returns the number of rows that were deleted.
DELETE FROM table_name WHERE column_name=some_value;
Without the WHERE clause all rows are deleted.
<!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>Deleting Data in a Database</title>
<meta Name="Author" Content="Hann So">
</head>
<body>
<p>
<?php

if (isset($_POST['submit'])) {
		process_form();
	}
	else {
		if (isset($_GET['id'])) {
			$id = $_GET['id'];
		}
		display_form($id);// display form for the first time
	}

function display_form($id) {
	echo <<<HTML
	<h2>Deleting Data in a Database</h2>
	<form action = "$_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 />
	blog_id:
	<input type="text" name="blog_id" size="50" value="$id" />
	<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]");

	$blog_id = stripslashes(trim($_POST[blog_id]));


	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
		$query = "DELETE FROM " . TABLE_NAME . " WHERE blog_id=$blog_id LIMIT 1";
		// run the query
		$r = mysql_query($query);
		// report on the result
		// mysql_affected_rows gets the number of rows affected by the previous MySQL operation.
		// if one row is affected then return true.
		if (mysql_affected_rows()==1) {
			echo "<p>The blog entry has been deleted.</p>";
			// close the connection
			mysql_close($link);
		}
		else {
			die ("<p>Could not delete the entry because: ". mysql_error(). "</p>");
		}
	}
	else {
		die ("<p>Could not connect to MySQL because: ". mysql_error(). "</p>");
	}
	echo "<p><a href=\"$_SERVER[SCRIPT_NAME]\">Try again?</a></p>\n";
	echo "<p><a href=\"example_r.php\">Retrieve data?</a></p>\n";

}

?>
</p>
</body>
</html>
View the effect