Help with PHP and MYSQL select function -

i creating browser statistics script in php.
when php finds match in table how retrieve row , pull 3 fields of table separate variables.

my table rows (browser, version, amount)

so want select tb

browser = $browser , version = $version.
when happens how add 1 amount field , resubmit row. without altering else. below code have.

$browser_name= "msie"; $version = "7"; $query = ("select * $tb    browser = '$browser_name' , version = '$version'"); $result = mysql_query($query); $count = mysql_num_rows($result); if($count == 1) {   $mysql = ("select * $tb      browser = '$browser_name' , version = '$version'");    //code add 1 amount here  } else {   //if browser not detected insert fresh row.   $mysql = "insert $tb (browser, version, amount)     values ('$browser_name', '$version', 1)"; } 

i have been looking around answers ages tell me how select information out of db whole.

update table set amount_field = amount_field + 1 browser = '$browser_name' , version = '$version' 

i don't understand why make twice same select.