Got it, let's break this down step by step—since you already have MySQL basics down, we'll focus on tying that into your Discord bot with discord.js. The core goal is: when a user sends a message, verify if their ID exists in your database; if not, add them with default level/XP values.

1. First: Set Up Your MySQL Table #

Let's start with the right table structure. Create a table (we'll call it member_levels) to store each user's Discord ID, level, and XP. Run this SQL in your MySQL client:

CREATE TABLE IF NOT EXISTS member_levels (
    user_id VARCHAR(255) NOT NULL PRIMARY KEY,
    level INT DEFAULT 1,
    xp INT DEFAULT 0
);

• We use VARCHAR for user_id because Discord IDs are large numeric strings—storing them as numbers can cause overflow issues in some cases.
• DEFAULT 1 and DEFAULT 0 ensure new users start at level 1 with 0 XP automatically, so you don't have to specify those values every time you add someone.

2. Connect MySQL to Your Discord.js Bot #

We'll use the mysql2 library (it supports promises, which makes async code way cleaner). First install it:

npm install mysql2

Then set up a connection pool in your bot code (connection pools are better than single connections for bots—they reuse connections efficiently instead of creating/destroying them every time):

const mysql = require('mysql2/promise');

// Create a connection pool with your MySQL credentials
const pool = mysql.createPool({
    host: 'your-host', // usually 'localhost' if running locally
    user: 'your-mysql-username',
    password: 'your-mysql-password',
    database: 'your-database-name',
    waitForConnections: true,
    connectionLimit: 10,
    queueLimit: 0
});

Replace the placeholder values with your actual MySQL login details.

3. Core Function: Check User Existence & Create if Missing #

Now let's write an async function that takes a user ID, checks if they're in the database, and adds them if they aren't. We'll use async/await to handle the asynchronous database calls smoothly.

async function checkOrCreateMember(userId) {
    try {
        // First, check if the user already exists
        const [rows] = await pool.execute('SELECT * FROM member_levels WHERE user_id = ?', [userId]);
        
        if (rows.length === 0) {
            // User doesn't exist—insert them with default level/XP
            await pool.execute('INSERT INTO member_levels (user_id) VALUES (?)', [userId]);
            console.log(`Added new user to database: ${userId}`);
        } else {
            console.log(`User ${userId} is already in the database`);
        }
    } catch (error) {
        console.error('Error checking/creating member:', error);
    }
}

• The ? in the SQL queries are placeholders—this prevents SQL injection, which is critical for security (never concatenate user input directly into SQL strings!).
• We wrap everything in a try/catch to handle any database errors (like connection drops or invalid queries) gracefully.

4. Hook the Function into Your Message Event #

Finally, connect this function to your bot's messageCreate event so it runs every time a user sends a message:

const { Client, GatewayIntentBits } = require('discord.js');

const client = new Client({
    intents: [
        GatewayIntentBits.Guilds,
        GatewayIntentBits.GuildMessages,
        GatewayIntentBits.MessageContent // Required to read message content
    ]
});

client.on('messageCreate', async (message) => {
    // Ignore bot messages to avoid cluttering the database
    if (message.author.bot) return;

    // Check if the user exists, create them if not
    await checkOrCreateMember(message.author.id);

    // From here, you can add XP/level update logic, e.g.:
    // await pool.execute('UPDATE member_levels SET xp = xp + 10 WHERE user_id = ?', [message.author.id]);
});

client.login('your-bot-token');

• Don't forget to enable the required intents in your Discord Developer Portal (Guilds, GuildMessages, MessageContent)—without these, your bot won't receive message events.
• Ignoring bot messages prevents unnecessary database calls from other bots interacting with your server.

Quick Pro Tips #

• If you need to fetch the user's level/XP after checking, modify the function to return rows[0] if the user exists, or the newly inserted data.
• For high-traffic servers, consider adding a small cooldown to XP updates so users can't spam messages to farm XP.
• Always test your database queries separately first to make sure they work before tying them into your bot.

内容的提问来源于stack exchange，提问作者DR_BOMBAY