如何从两个表创建JSON数据

import json
import pymysql

# 连接数据库
conn = pymysql.connect(host='localhost', user='username', password='password', db='database')
cursor = conn.cursor()

# 查询表A和表B的数据
cursor.execute('SELECT a1, a2 FROM tableA')
dataA = cursor.fetchall()

cursor.execute('SELECT b1, b2 FROM tableB')
dataB = cursor.fetchall()

# 创建JSON对象
json_data = {}

# 添加表A的数据到JSON对象
json_data['tableA'] = []
for row in dataA:
    json_data['tableA'].append({'a1': row[0], 'a2': row[1]})

# 添加表B的数据到JSON对象
json_data['tableB'] = []
for row in dataB:
    json_data['tableB'].append({'b1': row[0], 'b2': row[1]})

# 将JSON对象转换为字符串
json_str = json.dumps(json_data)

# 打印JSON字符串
print(json_str)

# 关闭数据库连接
cursor.close()
conn.close()