Question regarding the practical

Language: PHP
if form was submitted
//do this and include any required html
else 
//show form and include any required html

Language: PHP
<?php 
 
 
$db_handle = mysql_connect("localhost", "root" , "")
  or die("Could not connect: " . mysql_error());
mysql_select_db(';registration';, $db_handle)
  or die(mysql_error());
 
  switch ($_GET[';action';]) {
   case "add":
    switch ($_GET[';type';]) {
	 case "course":
	   $sql = "INSERT INTO course
	            (course_name)
				VALUES (';" . $_POST[';course_name';] . "';)";
				break;
			}
			break;
		}
	if (isset($sql) && !empty($sql)) {
	 echo "<!--" . $sql . "-->";
	 $result = mysql_query($sql)
	  or die("Invalid query: " . mysql_error());
 
 ?>

Language: PHP
if (isset($sql) && !empty($sql)) {
	 echo "<!--" . $sql . "-->";
	 $result = mysql_query($sql)
	  or die("Invalid query: " . mysql_error());
}

Language: PHP
$id = $_GET[';id';];
 
$result=mysql_query("DELETE FROM table_name where id=$id");
 
echo "Deleted!";
 
?>

Language: PHP
case ';dob';:
$pattern = "/^[\d]{4}-[\d]{2}-[\d]{2}$/";

Language: PHP
if (preg_match(';/\\A(?:^((\\d{2}(([02468][048])|([13579][26]))[\\-\\/\\s]?((((0?[13578])|(1[02]))[\\-\\/\\s]?((0?[1-9])|([1-2][0-9])|(3[01])))|(((0?[469])|(11))[\\-\\/\\s]?((0?[1-9])|([1-2][0-9])|(30)))|(0?2[\\-\\/\\s]?((0?[1-9])|([1-2][0-9])))))|(\\d{2}(([02468][1235679])|([13579][01345789]))[\\-\\/\\s]?((((0?[13578])|(1[02]))[\\-\\/\\s]?((0?[1-9])|([1-2][0-9])|(3[01])))|(((0?[469])|(11))[\\-\\/\\s]?((0?[1-9])|([1-2][0-9])|(30)))|(0?2[\\-\\/\\s]?((0?[1-9])|(1[0-9])|(2[0-8]))))))(\\s(((0?[0-9])|(1[0-9])|(2[0-3]))\\:([0-5][0-9])((\\s)|(\\:([0-5][0-9])))?))?$)\\z/';, $date)) {
    // date is valid
} else {
    // date is invalid
}

Language: PHP
<?php 
 
$date_format = ';Y-m-d';;
$input = $_POST[';date';]';; // or where ever you get it from
 
$input = trim($input);
$time = strtotime($input);
 
$is_date_valid = date($date_format, $time) == $input;
 
print "Valid? ".($is_date_valid ? ';yes'; : ';no';); // this is like using an if/else, just another way 
 
?>

Language: PHP
<?php
$db_handle = mysql_connect("localhost", "root" , "")
  or die("Could not connect: " . mysql_error());
mysql_select_db(';registration';, $db_handle)
  or die(mysql_error());
 
 $coursesql="SELECT*FROM course";
 
$id = $_GET[';cid';];
 
$result=mysql_query("DELETE FROM course WHERE cid=$id");
 
echo "Deleted!";
?>
 
 
<p><a href="course.php">Delete another course</a> OR <a href="course_man.php">Back to course list</a></p>

Language: PHP
function sanitise($reg_data){
	$count = count($reg_data);
	for($i = 0; $i < $count; $i++){
		$reg_data[$i] = strip_tags($reg_data[$i]);
		$reg_data[$i] = trim($reg_data[$i]);
		$reg_data[$i] = mysql_real_escape_string($reg_data[$i]);
		$reg_data[$i] = htmlspecialchars($reg_data[$i]);
		$reg_data[$i] = htmlentities($reg_data[$i]);
		if (get_magic_quotes_gpc()) {
		   $reg_data[$i] = stripslashes($reg_data[$i]);
	   }
	}
	return $reg_data;
}

Language: PHP
$result2 = mysql_query ("DELETE FROM course_student where cid = $id");