未定義指數誤差arrya

Question

我正在查詢數據庫，如下所示：現在

$result=mysql_query("SELECT name,items FROM mytable WHERE price='$price'"); 

，我想創建一個數組來插入是值這個查詢的結果E'G假設這是得到的數據：

name sellerid quantity 
john  12  10 
joel  23  20 
brian  40  10 

i.ve插入這個數據到一個數組，需要處理它（這是一個交易平臺），讓我們說，用戶想購買從數據25項。該數組，所以爲了達到這個目的，腳本必須從joel中取​​10個john項和15個joel項（加起來爲25），然後設置t繼承物品的剩餘價值，即約翰的物品= 0和喬爾的物品= 5。

這是code.i我在這條線得到一個錯誤約未定義指數

$assignedQuantityPerUser[ $row[ "sellerid" ] ] += $totalUnitsOrdered; 

這是代碼的其餘部分：

$query="SELECT itemquantity,sellerid FROM mytable WHERE price='$price'";      
//it is a table containing data about people selling their commoditities and the   program matches buyers and sellers by price 
$foundItems = array(); 

// likely to be a parameter of a function... 
$totalUnitsOrdered = 25; 

// maps user to amount assigned from him 
$assignedQuantityPerUser = array(); 


while ($row = mysql_fetch_assoc($cursor)) { 

// Still order Quantity left? 
if (0 < $totalUnitsOrdered) { 

    if ($row[ "itemquantity" ] <= $totalUnitsOrdered) { 

// assign all of $row[ "items" ] 
$totalUnitsOrdered       -= 0 + $row[ "itemquantity" ]; 
    $assignedQuantityPerUser[ $row[ "sellerid" ] ] += 0 + $row[ "itemquantity" ]; 
**//this is where in getting an error:r[ $row[ "sellerid" ] is an undefined index** 
} else { 

    // assign all the rest: $totalUnitsOrdered 
    $totalUnitsOrdered       = 0; 
    $assignedQuantityPerUser[ $row[ "sellerid" ] ] += $totalUnitsOrdered; 

} 

} 


$newItem[] = $row[ "sellerid" ]; 
$newItem[] = $row[ "itemquantity" ]; 

// Append $newItem to the end of $foundItems 
$foundItems[] = $newItem; 

} // while 

親切assist.thanks。

Answer 1

初始化值使用它之前：

if (!isset($assignedQuantityPerUser[$row["sellerid"]])) { 
    $assignedQuantityPerUser[$row["sellerid"]] = 0; 
} 
$assignedQuantityPerUser[$row["sellerid"]] += $totalUnitsOrdered;