Introduction

Turi Create connects with a database through Python DBAPI2, which is a standard written to encourage database providers to expose a common interface for executing SQL queries when making Python modules for their database. Common usage of a DBAPI2-compliant module from Python looks something like this:

import sqlite3
conn = sqlite3.connect('example.db')
c = conn.cursor()

# Create table
c.execute('''CREATE TABLE stocks
             (date text, trans text, symbol text, qty real, price real)''')

# Insert a row of data
c.execute("INSERT INTO stocks VALUES ('2006-01-05','BUY','RHAT',100,35.14)")

# Save (commit) the changes
conn.commit()

c.execute("SELECT * FROM stocks")
results = c.fetchall()

(example adapted from here)

SFrame offers a DBAPI2 integration that enables you to read and write SQL data in a similar, concise fashion. Using the connection object in the previous example, here is how you would read the data as an SFrame using the from_sql method:

import turicreate as tc
stocks_sf = tc.SFrame.from_sql(conn, "SELECT * FROM stocks")

If you would like to then write this table to the database, that's easy too, using the to_sql method. to_sql simply attempts to append to an already existing table, so if you intend to write the data to a new table in your database, then you must use the "CREATE TABLE" syntax, including the type syntax supported by your database. Here's an example of creating a new table and then appending more data to the table.

import datetime as dt
c = conn.cursor()

c.execute('''CREATE TABLE more_stocks
             (date text, trans text, symbol text, qty real, price real)''')
c.commit()
stocks_sf.to_sql(conn, "more_stocks")

# Append another row
another_row = tc.SFrame({'date':[dt.datetime(2006, 3, 28)],
                         'trans':['BUY'],
                         'symbol':['IBM'],
                         'qty':[1000],
                         'price':[45.00]})
another_row.to_sql(conn, "more_stocks")

That is all there is to know to get started using SFrames with Python DBAPI2 modules! For more details you can consult the API documentation of from_sql and to_sql. Currently, we have tested our DBAPI2 support with these modules:

• MySQLdb
• psycopg2
• sqlite3

This means that our DBAPI2 support may or may not work on other modules claiming to be DBAPI2-compliant. If you run into errors, let us know by filing a github issue.