You are defining DB_NAME
inside the MetacriticPipeline
class, move it at the top of the script (or better move to scrapy settings):
from __future__ import print_function
from metacritic.items import MetacriticItem
from mysql.connector import errorcode
import mysql.connector
import json
DB_NAME = 'metacritic'
class MetacriticPipeline(object):
...