Notice: Undefined variable: _SESSION in C:\xampp\htdocs\2\ShowOrder.php on line 3

Notice: Trying to access array offset on value of type null in C:\xampp\htdocs\2\ShowOrder.php on line 3

Fatal error: Uncaught Error: Call to undefined function mysql_query() in C:\xampp\htdocs\2\ShowOrder.php:6 Stack trace: #0 {main} thrown in C:\xampp\htdocs\2\ShowOrder.php on line 6