feat: Most of Item and Order controllers

api/queries/ItemQueries.go

@@ -10,13 +10,23 @@ INSERT INTO item_price_history(item_id, price) VALUES ($1, $2);
 
 const SET_ITEM_PRICE_VALID_TO_DATE = `
 UPDATE item_price_history SET valid_to = now() 
-FROM (
-	SELECT item_id, MAX(valid_from) FROM item_price_history WHERE item_id = $1
-) as o
-WHERE item_id IN o.item_id
+WHERE item_id IN (
+	SELECT item_id FROM item_price_history WHERE item_id = $1 ORDER BY valid_from DESC LIMIT 1
+)
 `
 
-const GET_ITEM_PRICE = `
+const GET_CURRENT_ITEM_PRICE = `
+SELECT
+	i.id,
+	i.item_name,
+	iph.price AS unit_price
+	FROM item i
+	INNER JOIN item_price_history iph ON iph.item_id = i.id
+		AND i.id = $1
+	ORDER BY iph.valid_from DESC
+	LIMIT 1;
+`
+const GET_ORDER_ITEM_PRICE = `
 SELECT
 	oi.item_id,
 	oi.order_id,