Question

this is my working code:

while ($list = mysql_fetch_assoc($result)) {
$sql2 = "SELECT * FROM stock WHERE gID=".$list['gID'];
$result2 = mysql_query($sql2, $conn) or trigger_error("SQL", E_USER_ERROR);
$totalgid = mysql_num_rows($result2);
$sql3 = "SELECT * FROM stockcount WHERE gID=".$list['gID']." AND date='".$list['date']."' AND affectstock=1";
$result3 = mysql_query($sql3, $conn) or trigger_error("SQL", E_USER_ERROR);
$dategid = mysql_num_rows($result3);
$calculategid = $totalgid - $dategid;
    if ($calculategid < 0) {

    if(isset($arr[$list['date']][$list['gID']])){
    //increment
} else {
    //set to initial value of 1
    $arr[$list['date']][$list['gID']]=$calculategid;
}

    }

}
print_r($arr);

Answer 1

do you have a loop outside this that is something like foreach($someList as $list){ ...do this code... }? I only ask because you should never have duplicate values because if you try to set a value into the same exact key, will overwrite the previous value. I can only assume based on the code you posted that you are appending this array to another array inside a loop. If that is the case, something like this might help:

//initialize the output array
$arr = array();
//loop through somelist
foreach($someList as $list){
    //check if the key exists, if so increment.
    if(isset($arr[$list['date']][$list['gID']])){
        //increment
        $arr[$list['date']][$list['gID']]++;
    } else {
        //set to initial value of 1
        $arr[$list['date']][$list['gID']]=1;
    }
}
print_r($arr);

essentially, just check if the key isset() and if so, increment, if not set to 1.