how to sum columns in phpmyadmin

$p=runsql("select sum(gheymat) as a from addcart where addcart.iduser=$user[iduser] "); this in my query how to Get a in $p and Pour in Variable Like $a and set in $c where "final"=> $c=updaterecord("tblgheymatekoli",array("final"=>),"iduser='$iduser'");

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