Why am I getting this MySQL error with node?

Question

I have connected to the database on MySQL, and was able to input data to a table. However, I am not able to input data to another table when it seems that I'm using the exact same method to achieve the input. Below is the code that works:

const mysql = require('mysql');
const connectionPool = mysql.createPool({
    connectionLimit: 1,
    host: "localhost",
    user: "dg",
    password: "123456",
    database: "legends_database",
    debug: false
});
exports.addUser = (Username, Email, Password, response) => {
    //Build query
    let sql = "INSERT INTO user (Username, Email, Password) " +
    "       VALUES ('" + Username + "','" + Email + "'," + Password +")";
    
    //Execute query
    connectionPool.query(sql, (err, result) => {
        if (err){//Check for errors
            let errMsg = "{Error: " + err + "}";
            console.error(errMsg);
            response.status(400).json(errMsg);
        }
        else{//Send back result
            response.send("{result: 'User added successfully'}");
        }
    });
}

I have copied this code and made changes and below is the code that gives me an error.

const mysql = require('mysql');
const connectionPool = mysql.createPool({
    connectionLimit: 1,
    host: "localhost",
    user: "dg",
    password: "123456",
    database: "legends_database",
    debug: false
});
exports.addPost = (Question_Title, Answer_Paragraph, response) => {
    //Build query
    let sql = "INSERT INTO answer (Question_Title, Answer_Paragraph) " +
    "       VALUES ('" + Question_Title + "','" + Answer_Paragraph  +")";
    
    //Execute query
    connectionPool.query(sql, (err, result) => {
        if (err){//Check for errors
            let errMsg = "{Error: " + err + "}";
            console.error(errMsg);
            response.status(400).json(errMsg);
        }
        else{//Send back result
            response.send("{result: 'Post added successfully'}");
        }
    });
}

This is the error I'm getting:

Data received: {"Question_Title":"Test_Question","Answer_Paragraph":"Test_Answer"}
{Error: Error: ER_PARSE_ERROR: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ''Test_Answer)' at line 1}

Answer 1

At first writing queries like this is SQL injection prone, so get rid of this. But if you're using for educational/self-use purposes only - here's my point: I see odd number of single quotes so it seems like the error comes from there(The error message just says that you have a syntax error). So try to write your query like this:

let sql = `INSERT INTO answer (Question_Title, Answer_Paragraph) VALUES ("${Question_Title}","${Answer_Paragraph}");