i m working in PHP since one year, but now a days i got this way to assign post data value directly using name attribute . i m really curious to know the documentation about it.please refere me link regarding this .

i explain by example

here is my form

<form method="post" action="">
<input type="text" name="userName" id="userName">
<input type="submit" name="doit" value="submit">
</form>

to get the post data i always use

$somevar=mysql_real_escape_string($_POST['userName']);

but now i see another way

$somevar= "userName";

i just want to know that is it safe n easy way??