PHP Session Management and MySQL Database Interaction

Starting a Session and Destroying Variables (inicio.php)

session_start();
unset($_SESSION["host"]);

Creating a Session and Attempting a Connection (marco.php)

session_start();
$conn = @mysql_connect($host, $user, $password) or die("Incorrect user or password");
@mysql_select_db($db, $conn) or die("Cannot open the DB");

Assigning Connection Parameters to Session Variables

$_SESSION["host"] = $host;
$_SESSION['User'] = $user;

Starting a Session, Connecting to the Database, and Sending an Insertion Query (altas.php)

<?
 session_start();
 $conn = mysql_connect($host, $user, $password) or die("Incorrect user or password");
 mysql_select_db($db, $conn) or die("Not selected");
 $query = "insert into departments values ($dep, '$nom', '$crazy')";
 $result = mysql_query($query, $connection);
?>

Saving the Number of Affected Rows

$rows = mysql_affected_rows($conn);

Handling Insertion Results and Errors

If 0, the row has been inserted into the table. If 1062, the key is duplicated and cannot be added. Otherwise, display the error number and description.

if (mysql_errno($conexion) == 0) {
 echo "Inserted<center><h2>NEWS</center></h2>";
} else {
 if (mysql_errno($conexion) == 1062) {
 echo "<center><h2>NEWS duplicate key. Cannot insert</center></h2>";
 } else {
 $numeroERROR = mysql_errno($conexion);
 $descripcionERROR = mysql_error($conexion);
 echo "Error Number: $numeroERROR Description: $descripcionERROR";
 }
}

Starting a Session and Connecting to the Database (bajas.php)

<?
 session_start();
 $db = mysql_connect($host, $user, $password) or die("Incorrect user or password");
 mysql_select_db($db, $conn) or die("Not selected");
?>

Queries for Data Deletion and Selection

$query1 = "delete from departments where dept_no = $dep";
$query2 = "Select * from departments where dept_no = $dep";

Fetching Data into an Array

$row = mysql_fetch_array($result, $conn);

Assigning Table Data to Variables

$dept_no = $row[dept_no];
$dNAME = $row[dNAME];
$loc = $row[loc];