pyodbc.connect() works, but not sqlalchemy.create_engine().connect()

KOB picture KOB · Jun 26, 2017 · Viewed 7.6k times · Source

I am attempting to write a Python script that can take Excel sheets and import them into my SQL Server Express (with Windows Authentication) database as tables. To do this, I am using pandas to read the Excel files into a pandas DataFrame, I then hope to use pandas.to_sql() to import the data into my database. To use this function, however, I need to use sqlalchemy.create_engine().

I am able to connect to my database using pyodbc alone, and run test queries. This conection is done with the followng code:

def create_connection(server_name, database_name):
    config = dict(server=server_name, database= database_name)

    conn_str = ('SERVER={server};DATABASE={database};TRUSTED_CONNECTION=yes')

    return pyodbc.connect(r'DRIVER={ODBC Driver 13 for SQL Server};' + conn_str.format(**config))

...

server = '<MY_SERVER_NAME>\SQLEXPRESS'
db = '<MY_DATABASE_NAME>

connection = create_connection(server, db)
cursor = connection.cursor()
cursor.execute('CREATE VIEW test_view AS SELECT * FROM existing_table')
cursor.commit()

However, this isn't much use as I can't use pandas.to_sql() - to do so I need an engine from sqlalchemy.create_engine(), but I am struggling to figure out how to use my same details in my create_connection() function above to successfully create an engine and connect to the database.

I have tried many, many combinations along the lines of:

engine = create_engine("mssql+pyodbc://@C<MY_SERVER_NAME>\SQLEXPRESS/<MY_DATABASE_NAME>?driver={ODBC Driver 13 for SQL Server}?trusted_connection=yes")
conn = engine.connect().connection

or

engine = create_engine("mssql+pyodbc://@C<MY_SERVER_NAME>\SQLEXPRESS/<MY_DATABASE_NAME>?trusted_connection=yes")   
conn = engine.connect().connection

Answer

Gord Thompson picture Gord Thompson · Jun 26, 2017

A Pass through exact Pyodbc string works for me from Python 3.6 on Windows:

from sqlalchemy import create_engine
import urllib
conn_str = (
    r'Driver=ODBC Driver 17 for SQL Server;'
    r'Server=(local)\SQLEXPRESS;'
    r'Database=myDb;'
    r'Trusted_Connection=yes;'
)
quoted_conn_str = urllib.parse.quote_plus(conn_str)
engine = create_engine(f'mssql+pyodbc:///?odbc_connect={quoted_conn_str}')
cnxn = engine.connect()
rows = cnxn.execute("SELECT name FROM sys.tables").fetchall()
print(rows)