Created database logic for nested recipes (references #77)

migrations/0043.sql

@@ -0,0 +1,25 @@
+CREATE TABLE recipes_nestings (
+	id INTEGER NOT NULL PRIMARY KEY AUTOINCREMENT UNIQUE,
+	recipe_id INTEGER NOT NULL,
+	includes_recipe_id INTEGER NOT NULL,
+	row_created_timestamp DATETIME DEFAULT (datetime('now', 'localtime')),
+
+	UNIQUE(recipe_id, includes_recipe_id)
+);
+
+CREATE VIEW recipes_nestings_resolved
+AS
+WITH RECURSIVE r1(recipe_id, includes_recipe_id)
+AS (
+	SELECT id, id
+	FROM recipes
+	
+	UNION ALL
+	
+	SELECT rn.recipe_id, r1.includes_recipe_id
+	FROM recipes_nestings rn, r1 r1
+	WHERE rn.includes_recipe_id = r1.recipe_id
+	LIMIT 100 -- This is just a safety limit to prevent infinite loops due to infinite nested recipes
+)
+SELECT *
+FROM r1;