ajax调用mysql数据库数据库

// 示例代码：服务器端设置CORS头部信息
app.use((req, res, next) => {
  res.header('Access-Control-Allow-Origin', '*');
  res.header('Access-Control-Allow-Methods', 'GET, POST, PUT, DELETE');
  res.header('Access-Control-Allow-Headers', 'Content-Type');
  next();
});

// 示例代码：设置AJAX请求超时时间
$.ajax({
  url: 'your-api-endpoint',
  timeout: 10000, // 10秒
  success: function(data) {
    // 处理成功响应
  },
  error: function(xhr, status, error) {
    if (status === 'timeout') {
      // 处理超时错误
    }
  }
});

// 示例代码：使用参数化查询
const mysql = require('mysql');
const connection = mysql.createConnection({
  host: 'localhost',
  user: 'user',
  password: 'password',
  database: 'database'
});

connection.connect();

const userId = req.body.userId;
const sql = 'SELECT * FROM users WHERE id = ?';
connection.query(sql, [userId], (error, results) => {
  if (error) throw error;
  console.log(results);
});

connection.end();