import sqlite3
con = sqlite3.connect(':memory:')#连接数据库
data.to_sql('data',con)
print(list(data))
print('查看分类变量的取值')
print('-'*16)
for i in list(data[['district','roomnum','hall','C_floor','school','subway']]):
    s = pd.read_sql_query('SELECT DISTINCT %s from data' % i,con)
    print(s)
    print('-'*16)