Unable to fetch data from database using Nodejs

I am working with Nodejs and using expressjs for API’S,Right now i am getting “undefined” in console.log (coming from model), How can i fetch data using express js ?

const sendotps = async (req, res) => {
    var phone_number=req.body.phone_number;
    if (!phone_number || !phone_number.trim() || phone_number == null || phone_number < 10)
        return res.status(400).send({ statusCode: 400, statusMessage: 'Bad Request', message: 'Enter valid mobile number', data: null });
    try {
        const result= await User.sendOtp(phone_number);
        console.log('result is '+ result);
        if(result!"notexist")
            {
                    // further code
            }
        else
            {
                    // further code
            }   
    } catch (err) {
        res.status(500).send({
            statusCode: 500,
            statusMessage: 'Internal Server Error',
            message: null,
            data: null,
        });
    }

Here is my “model file”(user.model)

static sendOtp(phone_number) {
        const sql2 = "SELECT * FROM users WHERE phone_number = '${phone_number}' AND is_registered='1'";
                const [rows2, fields2] = await pool.execute(sql2);
               if(rows2>0)
                {
                        return rows2;
                }
                else
                {
                        return "notexist";
                }
    }