//連接數據庫
$db = new PDO('mysql:host=localhost;dbname=mydatabase', 'username', 'password');
//構建查詢
$query = "SELECT * FROM table WHERE field LIKE :search";
//準備查詢
$stmt = $db->prepare($query);
//綁定參數
$stmt->bindValue(':search', '%'.$_GET['search'].'%');
//執行查詢
$stmt->execute();
//獲取結果
$results = $stmt->fetchAll(PDO::FETCH_ASSOC);
//將結果轉換為JSON
$json = json_encode($results);
//輸出JSON
echo $json;
