How to convert Amount from string to float in sql array?

Question

I have problem connected with function returning array from sql query. The problem is that I want to return category as string and amount as float. I think the best solution is to set in while loop to write that i want category as string and amount as float. But I don't know which function can I use to make this?

I was thinking to write something like this in while loop

while (($row = $stmt->fetch(PDO::FETCH_ASSOC)))
           {
                $data[] = [(string)$row['Category'],(float)$row['Amount']];
           }

But there is no result, that I expected.

public static function getPieChartIncomes()
{   
    if (empty(Income::$this->errors)) {

        $sql = "SELECT income_category_assigned_to_user_id as Category, SUM(amount) as Amount FROM incomes WHERE user_id = :userId  GROUP BY income_category_assigned_to_user_id ORDER BY SUM(amount)  DESC ";

        $db = static::getDB();
        $stmt = $db->prepare($sql);

        $stmt->bindValue(':userId', $_SESSION['user_id'], PDO::PARAM_INT);

        $stmt->execute();
           $data=array();
           while (($row = $stmt->fetch(PDO::FETCH_ASSOC)))
           {
                $data[] = $row;
           }
        return $data;
    }

    return false;
}


public static function convertDataToChartForm($data)
{
$newData = array();
$firstLine = true;

foreach ($data as $dataRow)
{
    if ($firstLine)
    {
        $newData[] = array_keys($dataRow);
        $firstLine = false;
    }

    $newData[] = array_values($dataRow);
}

return $newData;
}

Finally I wanted to achieve Array for google charts like this one:

$chartIncomesArray = Income::convertDataToChartForm($incomesArray);
json_encode($chartIncomesArray) =
['Category']['Amount']
['wynagrodzenie'][12.00]
['odsetki'][50.00]
etc.

Can anybody help me with this?

Answer 1

I solved my problem, deleting convertDataToChartForm($data) and changing getPieChartIncomes function to this:

public static function getPieChartIncomes()
    {   
        if (empty(Income::$this->errors)) {

            $sql = "SELECT income_category_assigned_to_user_id as Category, SUM(amount) as Amount FROM incomes WHERE user_id = :userId  GROUP BY income_category_assigned_to_user_id ORDER BY SUM(amount)  DESC ";

            $db = static::getDB();
            $stmt = $db->prepare($sql);

            $stmt->bindValue(':userId', $_SESSION['user_id'], PDO::PARAM_INT);

            $i = 1;
            $stmt->execute();
            $tablica = array();
            
               while (($row = $stmt->fetch(PDO::FETCH_ASSOC)))
               {
                $firstLine = true;
                if ($firstLine)
                {
                    $tablica[0] = array_keys($row);
                    $firstLine = false;
                }
                   $category = $row['Category'];
                   $amount = $row['Amount'];
                   $tablica[$i]=array(strval($category),floatval($amount));
                   $i++;
               }
            return $tablica;
        }

Thanks to while loop like now i can get table, where array keys are strings and another rows are: category as string and amount as int like this

['Category']['Amount']
['wynagrodzenie'][12.00]
['odsetki'][50.00]