如何获取上月至本月累计合计？

import datetime
import mysql.connector

# 获取当前年份和月份
current_date = datetime.datetime.now()
current_year = current_date.year
current_month = current_date.month

# 计算上个月的年份和月份
if current_month == 1:
    last_month_year = current_year - 1
    last_month_month = 12
else:
    last_month_year = current_year
    last_month_month = current_month - 1

# 连接数据库
cnx = mysql.connector.connect(user='username', password='password',
                              host='localhost', database='database_name')
cursor = cnx.cursor()

# 查询上月至本月的数据
query = "SELECT SUM(value) FROM table_name WHERE year = %s AND month BETWEEN %s AND %s"
cursor.execute(query, (last_month_year, last_month_month, current_month))
result = cursor.fetchone()[0]

# 关闭数据库连接
cursor.close()
cnx.close()

# 输出上月至本月累计合计值
print("上月至本月累计合计值为:", result)