如何将 mysqli_query 结果转换为 int？

Question

目前我正在开发一个移动图书馆应用程序，它需要借书。 我希望能够查看与可用图书总数相比已借出的图书数量。 我正在努力将mysqli_query结果转换为整数以与可用书籍总数进行比较。 如果这是一个简单的答案（我很新），我深表歉意，因为我做了很多挖掘，但找不到可以适应我的场景的答案。

<?php
require "conn.php";

$userID = "2";
$book_id = "1";

$mysql_qry = "select COUNT(*) from books_checked_out where bookID=$book_id";
$result = mysqli_query($conn, $mysql_qry);

//Somewhere here convert the $result into $quantity, which would be an int

if($quantity >= 2) {
    echo "more books checked out than in stock";
}
else if($quantity < 2) {
    echo "less books checked out than in stock";
}
?>

任何帮助表示赞赏，谢谢！

Answer 1

这将工作

$result = $result->fetch_array();
$quantity = intval($result[0]);

Answer 2

你可以这样做：

$userID = "2";
$book_id = "1";

$mysql_qry = "select COUNT(*) as quantity from books_checked_out where bookID=$book_id";
$result = mysqli_query($conn, $mysql_qry);

$row = mysqli_fetch_array($result, 'MYSQLI_ASSOC'); // Use something like this to get the result
$quantity = $row['quantity'];

if($quantity >= 2) {
    echo "more books checked out than in stock";
}
else if($quantity < 2) {
    echo "less books checked out than in stock";
}
?>

Answer 3

这应该有效。 请注意 SQL 注入。 另外，我对库存书籍的数据库进行了疯狂的猜测，这将需要更改。

require "conn.php";

$userID = "2";
$book_id = "1";

$mysql_qry = "SELECT 
(SELECT COUNT(*) FROM books_checked_out WHERE bookID='" . $book_id . "') as num1,
(SELECT COUNT(*) FROM books_in_stock WHERE bookID='" . $book_id . "') as num2";
$result = mysqli_query($conn, $mysql_qry);
$quantity = mysqli_fetch_assoc($result);

if($quantity['num1'] >= 2) {
    echo "more books checked out than in stock";
}
else {
    echo "less books checked out than in stock";
}
//If you want to see the difference you can do something like this.

echo "Checked Out" . $quantity['num1'] . '<br/>';
echo "In Stock" . $quantity['num2'] . '<br/>';

Answer 4

尝试使用intval("0".$row['quantity'])这会将您的数量转换为整数。