js 多个条件筛选数据库

const express = require('express');
const mysql = require('mysql');
const app = express();

const db = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: 'password',
    database: 'testdb'
});

db.connect();

app.get('/users', (req, res) => {
    const { age, gender, city } = req.query;
    let sql = 'SELECT * FROM users WHERE 1=1';
    const params = [];

    if (age) {
        sql += ' AND age = ?';
        params.push(age);
    }
    if (gender) {
        sql += ' AND gender = ?';
        params.push(gender);
    }
    if (city) {
        sql += ' AND city = ?';
        params.push(city);
    }

    db.query(sql, params, (err, results) => {
        if (err) throw err;
        res.json(results);
    });
});

app.listen(3000, () => {
    console.log('Server running on port 3000');
});

async function fetchUsers(age, gender, city) {
    const response = await fetch(`/users?age=${age}&gender=${gender}&city=${city}`);
    const users = await response.json();
    console.log(users);
}

fetchUsers(25, 'male', 'New York');