REST is a generally agreed-upon set of principles and constraints. They are recommendations, not a standard.
// inside /api/apiRoutes.js <- this can be place anywhere and called anything
const express = require('express');
// if the other routers are not nested inside /api then the paths would change
const userRoutes = require('./users/userRoutes');
const productRoutes = require('./products/productRoutes');
const clientRoutes = require('./clients/clientRoutes');
const router = express.Router(); // notice the Uppercase R
// this file will only be used when the route begins with "/api"
// so we can remove that from the URLs, so "/api/users" becomes simply "/users"
router.use('/users', userRoutes);
router.use('/products', productRoutes);
router.use('/clients', clientRoutes);
// .. and any other endpoint related to the user's resource
// after the route has been fully configured, we then export it so it can be required where needed
module.exports = router; // standard convention dictates that this is the last line on the file
Foreign keys are a type of table field used for creating links between tables. Like primary keys, they are most often integers that identify (rather than store) data. However, whereas a primary key is used to id rows in a table, foreign keys are used to connect a record in one table to a record in a second table.
Consider the following farms and ranchers tables.
The farm_id in the ranchers table is an example of a foreign key. Each entry in the farm_id (foreign key) column corresponds to an id (primary key) in the farms table. This allows us to track which farm each rancher belongs to while keeping the tables normalized.
If we could only see the ranchers table, we would know that John, Jane, and Jen all work together and that Jim and Jay also work together. However, to know where any of them work, we would need to look at the farms table.
Open SQLTryIT (Links to an external site.).
How many records in the products table belong to the category “confections”?
Now that we understand the basics of querying data from a single table, let’s move on to selecting data from multiple tables using JOIN operations.
We can use a JOIN to combine query data from multiple tables using a single SELECT statement.