Some more cleaning in tables

app/Migrations/create-schema.sql

@@ -36,20 +36,22 @@ CREATE TABLE IF NOT EXISTS orders (
 );
 
 --------------------------------------------
--- Recipe/Cookie related tables
+-- Raw materials, ingredients and recipes
 --------------------------------------------
 -- Notes: the unit type can be defined in terms 
 -- of volume or weight instead. Here we choose 
 -- to use static si-prefixes in relevant tables.
 
--- What types of ingredients do we handle
+-- What types of ingredients do we handle. 
+-- Not currently used, but kept as an example.
 CREATE TABLE IF NOT EXISTS ingredients (
     ingredient_id INTEGER PRIMARY KEY,
     ingredient_name VARCHAR(50) NOT NULL UNIQUE,
     preferred_unit VARCHAR(50) NOT NULL CHECK (preferred_unit IN ('g', 'ml'))
 );
 
--- What ingredients are in what cookies
+-- What ingredients are in what cookies?
+-- Glues together the cookies and ingredients, a 'recipe'.
 CREATE TABLE IF NOT EXISTS recipe_contents (
     cookie_id INT NOT NULL,
     ingredient_id INT NOT NULL,
@@ -61,6 +63,7 @@ CREATE TABLE IF NOT EXISTS recipe_contents (
 );
 
 -- Describes ingredients and stock.
+-- This should reference the ingredients table, but we'll keep it simple for now.
 CREATE TABLE IF NOT EXISTS raw_materials (
     ingredient_id INTEGER PRIMARY KEY,
     ingredient_name VARCHAR(50) NOT NULL UNIQUE,