GD是一個非常流行的圖像處理庫，可以在PHP中使用，可用于創建、編輯、和操縱圖像。其中一個主要的應用就是生成圖像驗證碼。

MySQL是一個開源的關系型數據庫管理系統，是PHP最流行的數據庫模塊之一，可用于儲存和操作數據。

// 應用GD庫創建驗證碼圖片
$width = 100;
$height = 40;
$length = 4;
$img = imagecreatetruecolor($width, $height);
$bgColor = imagecolorallocate($img, rand(200,250), rand(200,250), rand(200,250));
imagefill($img, 0, 0, $bgColor);
$codeSet = '0123456789';
$code = '';
for ($i = 0; $i< $length; $i++) {
$code .= $codeSet[rand(0, strlen($codeSet)-1)];
}
for ($i = 0; $i< rand(10, 20); $i++) {
$lineColor = imagecolorallocate($img, rand(150,200), rand(150,200), rand(150,200));
imageline($img, rand(0, $width), rand(0, $height), rand(0, $width), rand(0, $height), $lineColor);
}
for ($i = 0; $i< rand(4, 7); $i++) {
$fontFile = './fonts/' . rand(1, 3) . '.ttf';
$fontSize = rand(18, 24);
$x = $i * ($width / $length) + ($width / $length - $fontSize) / 2;
$y = rand($height/2, $height - $fontSize);
$fontColor = imagecolorallocate($img, rand(0,100), rand(0,100), rand(0,100));
$text = substr($code, $i, 1);
imagettftext($img, $fontSize, rand(-10, 10), $x, $y, $fontColor, $fontFile, $text);
}
header('Content-Type:image/png');
imagepng($img);
imagedestroy($img);
// 連接和查詢數據庫
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// 創建連接
$conn = mysqli_connect($servername, $username, $password, $dbname);
// 檢查連接是否成功
if (!$conn) {
die("Connection failed: " . mysqli_connect_error());
}
// 查詢數據
$sql = "SELECT * FROM Students WHERE Age >18";
$result = mysqli_query($conn, $sql);
if (mysqli_num_rows($result) >0) {
while($row = mysqli_fetch_assoc($result)) {
echo "Name: " . $row["Name"]. " - Age: " . $row["Age"]. "
";
}
} else {
echo "0 results";
}
mysqli_close($conn);