Question

此查询有效

SELECT id, username, password 
        FROM users
       WHERE (email = ?)
        LIMIT 1"
$stmt->bind_param('s', $email);
        $stmt->execute();
        $stmt->store_result();

这不是

SELECT id, username, password 
        FROM users
       WHERE (email = ? || username = ?)
        LIMIT 1"

需要同时使用电子邮件和用户名登录，而仅使用电子邮件无法登录

Answer 1

使用OR代替||

import 'package:flutter/material.dart';

void main() => runApp(new MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: new Policy(),
    );
  }
}

class Policy extends StatefulWidget {
  @override
  _PolicyState createState() => _PolicyState();
}

class _PolicyState extends State<Policy> {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: DefaultTabController(
        length: 3,
        child: Scaffold(
          appBar: AppBar(
            bottom: GradientTabBar(
              colors: [Theme.of(context).primaryColor, Colors.green],
              begin: Alignment.topCenter,
              end: Alignment.bottomCenter,
              tabBar: TabBar(
                //indicatorColor: Colors.white,
                tabs: [
                  Tab(icon: Icon(Icons.directions_car)),
                  Tab(icon: Icon(Icons.directions_transit)),
                  Tab(icon: Icon(Icons.directions_bike)),
                ],
              ),
            ),
            title: Center(child: Text('POLICY')),
          ),
          body: TabBarView(
            children: [
              Icon(Icons.directions_car),
              Icon(Icons.directions_transit),
              Icon(Icons.directions_bike),
            ],
          ),
        ),
      ),
    );
  }
}

class GradientTabBar extends StatefulWidget implements PreferredSizeWidget {
  // Gradiente properties
  final AlignmentGeometry begin;
  final AlignmentGeometry end;
  final List<Color> colors;

  final TabBar tabBar;

  GradientTabBar({
    Key key,
    @required this.colors,
    this.begin = Alignment.centerLeft,
    this.end = Alignment.centerRight,
    this.tabBar,
  }) : super(key: key);

  @override
  Size get preferredSize => tabBar.preferredSize;

  @override
  _GradientTabBarState createState() => _GradientTabBarState();
}

class _GradientTabBarState extends State<GradientTabBar> {
  @override
  Widget build(BuildContext context) {
    return Stack(
      children: <Widget>[
        Container(
          height: widget.preferredSize.height,
          decoration: BoxDecoration(
              gradient: LinearGradient(
            begin: widget.begin,
            end: widget.end,
            colors: widget.colors,
          )),
        ),
        widget.tabBar,
      ],
    );
  }
}

Answer 2

声明参数时，您可以列出所有类型，然后列出其后的变量，例如下面的示例；

$sql = "SELECT id, username, password FROM users WHERE (email = ? OR username = ?) LIMIT 1"

$stmt->bind_param('ss', $email, $username);

此外，正如Shahnawaz所说，请使用OR代替||。

在PHP中绑定多个参数

2 个答案: