import sqlalchemy
import pandas as pd
from functools import partial

class dataBase:
    def __init__(self, connection_string):
        self.engine = sqlalchemy.create_engine(connection_string)
        self.read_sql = partial(pd.read_sql, con = self.engine)
        self.read_sql_table = partial(pd.read_sql_table, con = self.engine)
        self.read_sql_query = partial(pd.read_sql_query, con = self.engine)

db = dataBase('blah blah connection string')
df = db.read_sql_table('tablename')  # note I don't need to specify con = engine
df.to_sql(con = ?)    # could use con = db.engine, but I'd prefer
                      # to specify that in the dataBase class somewhere

pd.DataFrame.to_sql = partial(pd.DataFrame.to_sql, con = my_engine)