将mySQL数据库中的数值分配给PHP变量时，最佳方法是什么？

Question

I'm attempting to grab a number value from a mySQL database using PHP. I'd like to use that number value for some calculations after I've assigned it's value to a variable. The number value is stored as a float in my database. My code attempts to connect to my database (which it does successfully), then pull a number value based on parameters passed on by my query, then apply that number value to a variable that I can use in my code. In my code below, I'm simply trying to print that value to make sure it's pulling properly. The result I get is this notice: Notice: Array to string conversion in /Users/max/Desktop/Sites/webprojects/prg/nba/percentchange.php on line 14 Array

Here's my code:

$mysqli = new mysqli('localhost', 'root', 'root', 'NBA');

            if (mysqli_connect_errno()) {
                echo '<p>Error: could not connect to database.</p>';
                exit;
            }

            $rank = "SELECT average FROM nbaCompRankings WHERE team = 'Celtics'";
            $result = $mysqli->query($rank);
            $currentRank = $result->fetch_assoc();

echo $currentRank;

The potential solutions I've found on this site use deprecated libraries, so I've been unsuccessful in a search for a solution. Thanks in advance for any help you can give!

Answer 1

Try This:

$result = $mysqli->query($rank);
while($row = $result->fetch_assoc()) {
    $currentRank = $row["average"];
}

You should really be preparing your statements though.

$team = 'Celtics';
$sql= "SELECT average FROM nbaCompRankings WHERE team = ?";
$stmt = $mysqli->prepare($sql);
$stmt->bind_param("s", $team);
$stmt->execute();
$stmt->bind_result($average);
while($stmt->fetch()) {
    $currentRank = $average;
}
$stmt->close();