Converter procedimentos armazenados

BEGIN
   DECLARE v_rentals INT;
   DECLARE v_out       INT;
   SELECT COUNT(*) INTO v_rentals
   FROM rental
   WHERE inventory_id = p_inventory_id;
   IF v_rentals = 0 THEN
      RETURN TRUE;
   END IF;
   SELECT COUNT(rental_id) INTO v_out
   FROM inventory LEFT JOIN rental USING(inventory_id)
   WHERE inventory.inventory_id = p_inventory_id
   AND rental.return_date IS NULL;
   IF v_out > 0 THEN
      RETURN FALSE;
   ELSE
      RETURN TRUE;
   END IF;
END

async function query(db, p_inventory_id) {
const v_rentals = await db.collection('rental').countDocuments(
   { inventoryId: p_inventory_id }
);
if (v_rentals === 0) {
   return true;
}
const v_out = await db.collection('inventory').aggregate([
   {
      $lookup: {
      from: 'rental',
      localField: 'inventoryId',
      foreignField: 'inventoryId',
      as: 'rentalData'
      }
   },
   {
      $match: {
      inventoryId: p_inventory_id,
      'rentalData.returnDate': { $exists: false }
      }
   },
   {
      $count: 'rentalId'
   }
   ]).toArray();
   if (v_out.length > 0 && v_out[0].rentalId > 0) {
      return false;
   } else {
      return true;
   }
   }

BEGIN
      DECLARE v_customer_id INT;
      DECLARE EXIT HANDLER FOR NOT FOUND RETURN NULL;
      SELECT customer_id INTO v_customer_id
      FROM rental
      WHERE return_date IS NULL
      AND inventory_id = p_inventory_id;
      RETURN v_customer_id;
   END

async Task<int?> Query(IMongoDatabase db)
{
   var rentalCollection = db.GetCollection<BsonDocument>("rental");
   var filter = Builders<BsonDocument>.Filter.Eq("inventoryId", p_inventory_id) & Builders<BsonDocument>.Filter.Eq("returnDate", null);
   var result = await rentalCollection.Find(filter).FirstOrDefaultAsync();
   return result != null ? result["customerId"].AsInt32 : (int?)null;
}

BEGIN
   SELECT inventory_id
   FROM inventory
   WHERE film_id = p_film_id
   AND store_id = p_store_id
   AND NOT inventory_in_stock(inventory_id);
   SELECT COUNT(*)
   FROM inventory
   WHERE film_id = p_film_id
   AND store_id = p_store_id
   AND NOT inventory_in_stock(inventory_id)
   INTO p_film_count;
END

void query(MongoDatabase db) {
   int p_film_id = 0;
   int p_store_id = 0;
   int p_film_count = 0;
   MongoCollection<Document> inventoryCollection = db.getCollection("inventory");
   Bson filter = Filters.and(Filters.eq("filmId", p_film_id), Filters.eq("storeId", p_store_id), Filters.not(inventory_in_stock("inventoryId")));
   FindIterable<Document> result = inventoryCollection.find(filter);
   for (Document doc : result) {
      System.out.println(doc.getInteger("inventoryId"));
   }
   p_film_count = (int) inventoryCollection.countDocuments(filter);
}