PHP中如何在Echo语句中嵌入HTML和PHP代码

php echo $displayBalance; ?>)完整代码示例<?php// 假设 $conn 是已建立的PDO连接，$user_id 是当前用户ID$stmt = $conn->prepare("SELECT balance_amount FROM balance WHERE user_id = ?");$stmt->execute([$user_id]);$displayBalance = 0; // 默认值if ($stmt->rowCount...