OpenPNE3の各テーブルでの大体の日毎のレコードの増加量を知る方法

import MySQLdb
import datetime

def row_count(table_name):
  global g_cur
  g_cur.execute('select count(*) from ' + table_name)
  one = g_cur.fetchone()
  return one[0]

def is_exist_created_at_column(table_name):
  global g_cur
  global g_dbname
  sql = "SELECT count(*) FROM  information_schema.columns WHERE table_schema = '" + g_dbname + "' AND table_name = '" + table_name + "' AND COLUMN_NAME = 'created_at'"
  g_cur.execute(sql)
  one = g_cur.fetchone()
  return one[0]

def row_zoukaryo(table_name):
  global g_cur
  global g_start_date
  global g_end_date
  sql = "select count(*) from " + table_name + " where created_at > \'" + g_start_date + "' AND created_at < '" + g_end_date + "'"
  g_cur.execute(sql)
  one = g_cur.fetchone()
  return one[0]

g_dbname = ""
g_unix_socket = ""
g_start_date = "2010-08-11 00:00:00"
g_end_date = "2010-08-18 00:00:00"
g_connect = MySQLdb.connect(user="", passwd="", db=g_dbname, host="", charset="utf8", unix_socket="")
g_cur = g_connect.cursor()

print g_start_date + "から" + g_end_date + "の間のデータ"
d = datetime.datetime.today()
print "テーブル名,",
print d.strftime("%Y-%m-%d %H:%M:%S") + "時点の総レコード数,",
print g_start_date + "から" + g_end_date + "の間の総増加レコード数,",
print g_start_date + "から" + g_end_date + "の間の1日平均増加レコード数"

g_cur.execute('show tables')
tables = g_cur.fetchall()
for table_name in tables:
  print table_name[0] + ',',
  row_c = row_count(table_name[0])
  print str(row_c) + ',',
  if( is_exist_created_at_column(table_name[0]) ):
    row_z = row_zoukaryo(table_name[0])
    print str(row_z) + ',',
    print str(row_z / 7)
  else:
    print ','
g_connect.close()