php predefine globle variable Superglobals — Superglobals are built-in variables that are always available in all scopes $GLOBALS — References all variables available in global scope $_SERVER — Server and execution environment information $_GET — HTTP GET variables $_POST — HTTP POST variables $_FILES — HTTP File Upload variables $_REQUEST — HTTP Request variables $_SESSION — Session variables $_ENV — Environment variables $_COOKIE — HTTP Cookies $php_errormsg — The previous error message $HTTP_RAW_POST_DATA — Raw POST data $http_response_header — HTTP response headers $argc — The number of arguments passed to script $argv — Array of arguments passed to script
make sure are created other wise create your table and add some data. for example : then run this query: SELECT first_name, last_name, ( CASE WHEN user_id < 3 THEN "Admin user" WHEN user_id = 3 THEN "editor user" ELSE "suscriber user" END) as role FROM users; the result output is : you can define query as per your requirement.