i have a table:

CREATE TABLE IF NOT EXISTS bands (
   id serial PRIMARY KEY,
   name VARCHAR UNIQUE NOT NULL,
   creationDate DATE not NULL,
   years  DATE not NULL
);

I only want to pass name and creation date. what i want is that years will return currentdate - creationDate. The problem is that I do not really know where i should correctly change my code, because im using Node project. My code looks like this:

const express = require("express");
const app = express();
const pool = require("./db");

app.use(express.json());
// Routes

app.post("/bands", async (req, res) => {
  try {
    const { name, creationDate } = req.body;
    const newBand = await pool.query(
      "INSERT INTO bands (name, creationDate,years) VALUES ($1, $2) RETURNING *",
      [name, creationDate]
    );
    res.json(newBand);
  } catch (err) {
    console.error(err.message);
  }
});

app.get("/bands", async (req, res) => {
  try {
    const allBands = await pool.query("SELECT * FROM bands");
    res.json(allBands);
    console.log(allBands);
  } catch (err) {
    console.error(err.message);
  }
});
app.get("/bands/:bandsName", async (req, res) => {
  console.log(req.params);
  const { bandsName } = req.params;
  try {
    const todo = await pool.query("SELECT * FROM bands WHERE name = $1", [
      bandsName,
    ]);
    res.json(todo.rows[0]);
  } catch (err) {
    console.error(err.message);
  }
});

app.put("/bands/:id", async (req, res) => {
  try {
    const { id } = req.params;
    const { name, creationDate } = req.body;
    const updateTodo = await pool.query(
      "UPDATE band SET name = $1,  creationDate = $2 WHERE id = $3",
      [name, creationDate, id]
    );
    res.json("Udało się, zaaktualizowane");
  } catch (err) {
    console.error(err.message);
  }
});
app.delete("/bands/:id", async (req, res) => {
  try {
    const { id } = req.params;
    const deleteTodo = await pool.query("DELETE FROM bands WHERE id = $1", [
      id,
    ]);
    res.json("Usunięto");
  } catch (err) {
    console.error(err.message);
  }
});

app.listen(3000, () => {
  console.log("server is listening on port 3000");
});

Can anyone tell me where should i change my code so "years" will automatically calculate without me having to put the data in postman?