sql magic for IPython, hopefully evolving into full SQL client. http://catherinedevlin.blogspot.com/
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README.rst
=========== ipython-sql =========== :Author: Catherine Devlin, http://catherinedevlin.blogspot.com Introduces a %sql (or %%sql) magic. Connect to a database, using SQLAlchemy connect strings, then issue SQL commands within IPython or IPython Notebook. .. image:: https://raw.github.com/catherinedevlin/ipython-sql/master/examples/writers.png :width: 600px :alt: screenshot of ipython-sql in the Notebook Examples -------- .. code-block:: python In [1]: %load_ext sql In [2]: %%sql postgresql://will:longliveliz@localhost/shakes ...: select * from character ...: where abbrev = 'ALICE' ...: Out[2]: [(u'Alice', u'Alice', u'ALICE', u'a lady attending on Princess Katherine', 22)] In [3]: result = _ In [4]: print(result) charid charname abbrev description speechcount ================================================================================= Alice Alice ALICE a lady attending on Princess Katherine 22 In [4]: result.keys Out[5]: [u'charid', u'charname', u'abbrev', u'description', u'speechcount'] In [6]: result[0][0] Out[6]: u'Alice' In [7]: result[0].description Out[7]: u'a lady attending on Princess Katherine' After the first connection, connect info can be omitted:: In [8]: %sql select count(*) from work Out[8]: [(43L,)] Connections to multiple databases can be maintained. You can refer to an existing connection by username@database .. code-block:: python In [9]: %%sql will@shakes ...: select charname, speechcount from character ...: where speechcount = (select max(speechcount) ...: from character); ...: Out[9]: [(u'Poet', 733)] In [10]: print(_) charname speechcount ====================== Poet 733 If no connect string is supplied, ``%sql`` will provide a list of existing connections; however, if no connections have yet been made and the environment variable ``DATABASE_URL`` is available, that will be used. For secure access, you may dynamically access your credentials (e.g. from your system environment or `getpass.getpass`) to avoid storing your password in the notebook itself. Use the `$` before any variable to access it in your `%sql` command. .. code-block:: python In [11]: user = os.getenv('SOME_USER') ....: password = os.getenv('SOME_PASSWORD') ....: connection_string = "postgresql://{user}:{password}@localhost/some_database".format(user=user, password=password) ....: %sql $connection_string Out[11]: u'Connected: some_user@some_database' You may use multiple SQL statements inside a single cell, but you will only see any query results from the last of them, so this really only makes sense for statements with no output .. code-block:: python In [11]: %%sql sqlite:// ....: CREATE TABLE writer (first_name, last_name, year_of_death); ....: INSERT INTO writer VALUES ('William', 'Shakespeare', 1616); ....: INSERT INTO writer VALUES ('Bertold', 'Brecht', 1956); ....: Out[11]: [] Bind variables (bind parameters) can be used in the "named" (:x) style. The variable names used should be defined in the local namespace .. code-block:: python In [12]: name = 'Countess' In [13]: %sql select description from character where charname = :name Out[13]: [(u'mother to Bertram',)] As a convenience, dict-style access for result sets is supported, with the leftmost column serving as key, for unique values. .. code-block:: python In [14]: result = %sql select * from work 43 rows affected. In [15]: result['richard2'] Out[15]: (u'richard2', u'Richard II', u'History of Richard II', 1595, u'h', None, u'Moby', 22411, 628) Results can also be retrieved as an iterator of dictionaries (``result.dicts()``) or a single dictionary with a tuple of scalar values per key (``result.dict()``) Assignment ---------- Ordinary IPython assignment works for single-line `%sql` queries: .. code-block:: python In [16]: works = %sql SELECT title, year FROM work 43 rows affected. The `<<` operator captures query results in a local variable, and can be used in multi-line ``%%sql``: .. code-block:: python In [17]: %%sql works << SELECT title, year ...: FROM work ...: 43 rows affected. Returning data to local variable works Connecting ---------- Connection strings are `SQLAlchemy`_ standard. Some example connection strings:: mysql+pymysql://scott:tiger@localhost/foo oracle://scott:tiger@127.0.0.1:1521/sidname sqlite:// sqlite:///foo.db mssql+pyodbc://username:password@host/database?driver=SQL+Server+Native+Client+11.0 .. _SQLAlchemy: http://docs.sqlalchemy.org/en/latest/core/engines.html#database-urls Note that ``mysql`` and ``mysql+pymysql`` connections (and perhaps others) don't read your client character set information from .my.cnf. You need to specify it in the connection string:: mysql+pymysql://scott:tiger@localhost/foo?charset=utf8 Note that ``impala`` connecion with `impyla`_ for HiveServer2 requires to disable autocommit:: %config SqlMagic.autocommit=False %sql impala://hserverhost:port/default?kerberos_service_name=hive&auth_mechanism=GSSAPI .. _impyla: https://github.com/cloudera/impyla Configuration ------------- Query results are loaded as lists, so very large result sets may use up your system's memory and/or hang your browser. There is no autolimit by default. However, `autolimit` (if set) limits the size of the result set (usually with a `LIMIT` clause in the SQL). `displaylimit` is similar, but the entire result set is still pulled into memory (for later analysis); only the screen display is truncated. .. code-block:: python In [2]: %config SqlMagic SqlMagic options -------------- SqlMagic.autocommit=<Bool> Current: True Set autocommit mode SqlMagic.autolimit=<Int> Current: 0 Automatically limit the size of the returned result sets SqlMagic.autopandas=<Bool> Current: False Return Pandas DataFrames instead of regular result sets SqlMagic.displaylimit=<Int> Current: 0 Automatically limit the number of rows displayed (full result set is still stored) SqlMagic.feedback=<Bool> Current: True Print number of rows affected by DML SqlMagic.short_errors=<Bool> Current: True Don't display the full traceback on SQL Programming Error SqlMagic.style=<Unicode> Current: 'DEFAULT' Set the table printing style to any of prettytable's defined styles (currently DEFAULT, MSWORD_FRIENDLY, PLAIN_COLUMNS, RANDOM) In[3]: %config SqlMagic.feedback = False Please note: if you have autopandas set to true, the displaylimit option will not apply. You can set the pandas display limit by using the pandas ``max_rows`` option as described in the `pandas documentation <http://pandas.pydata.org/pandas-docs/version/0.18.1/options.html#frequently-used-options>`_. Pandas ------ If you have installed ``pandas``, you can use a result set's ``.DataFrame()`` method .. code-block:: python In [3]: result = %sql SELECT * FROM character WHERE speechcount > 25 In [4]: dataframe = result.DataFrame() The bogus non-standard pseudo-SQL command ``PERSIST`` will create a table name in the database from the named DataFrame. .. code-block:: python In [5]: %sql PERSIST dataframe In [6]: %sql SELECT * FROM dataframe; .. _Pandas: http://pandas.pydata.org/ Graphing -------- If you have installed ``matplotlib``, you can use a result set's ``.plot()``, ``.pie()``, and ``.bar()`` methods for quick plotting .. code-block:: python In[5]: result = %sql SELECT title, totalwords FROM work WHERE genretype = 'c' In[6]: %matplotlib inline In[7]: result.pie() .. image:: https://raw.github.com/catherinedevlin/ipython-sql/master/examples/wordcount.png :alt: pie chart of word count of Shakespeare's comedies Dumping ------- Result sets come with a ``.csv(filename=None)`` method. This generates comma-separated text either as a return value (if ``filename`` is not specified) or in a file of the given name. .. code-block:: python In[8]: result = %sql SELECT title, totalwords FROM work WHERE genretype = 'c' In[9]: result.csv(filename='work.csv') PostgreSQL features ------------------- ``psql``-style "backslash" `meta-commands`_ commands (``\d``, ``\dt``, etc.) are provided by `PGSpecial`_. Example: .. code-block:: python In[9]: %sql \d .. _PGSpecial: https://pypi.python.org/pypi/pgspecial .. _meta-commands: https://www.postgresql.org/docs/9.6/static/app-psql.html#APP-PSQL-META-COMMANDS Installing ---------- Install the lastest release with:: pip install ipython-sql or download from https://github.com/catherinedevlin/ipython-sql and:: cd ipython-sql sudo python setup.py install Development ----------- https://github.com/catherinedevlin/ipython-sql Credits ------- - Matthias Bussonnier for help with configuration - Olivier Le Thanh Duong for ``%config`` fixes and improvements - Distribute_ - Buildout_ - modern-package-template_ - Mike Wilson for bind variable code - Thomas Kluyver and Steve Holden for debugging help - Berton Earnshaw for DSN connection syntax - Andrés Celis for SQL Server bugfix - Michael Erasmus for DataFrame truth bugfix - Noam Finkelstein for README clarification - Xiaochuan Yu for `<<` operator, syntax colorization - Amjith Ramanujam for PGSpecial and incorporating it here .. _Distribute: http://pypi.python.org/pypi/distribute .. _Buildout: http://www.buildout.org/ .. _modern-package-template: http://pypi.python.org/pypi/modern-package-template