I am working on node.js project for two days. This is my first node.js code. All the time I am confused with knex and Promises.

First I didn’t add “returns” after knex queries. But then my code never executed knex query. SO, I added “returns’, but this is confusing for me, to have multiple returns in each function. Please, check my code.

update_product_rating(13)     .then((affected) => {         console.log(affected);     });  function update_product_rating(product_id) {     return calculate_product_rating(product_id)         .then((rating) => {             rating = rating == null ? 0 : rating;             console.log('rating = ');             console.log(rating);             return knex('products')                 .where('id', product_id)                 .update('rating', rating);         }) }  function calculate_product_rating(product_id) {         // sum up all ratings     return knex('product_ingredients')         .join('ingredients', 'ingredients.id', '=', 'product_ingredients.ingredient_id')         .where("product_ingredients.product_id", product_id)         .sum('ingredients.rating_adjustments as adjustment')         .then(function (res) {             return res.adjustment;          }); }