fetchAll("SHOW COLUMNS FROM users LIKE 'bio'"); if (empty($columns)) { // 字段不存在,添加 $db->query("ALTER TABLE users ADD COLUMN bio TEXT AFTER avatar"); echo "✓ 成功添加 bio 字段\n"; } else { echo "✓ bio 字段已存在,无需迁移\n"; } echo "迁移完成!\n"; } catch (Exception $e) { echo "✗ 迁移失败:" . $e->getMessage() . "\n"; exit(1); }