To facilitate rapid experimentation with SQL queries, add a shell to run commands and display results.

Attached is minimal proof-of-concept modeled loosely on the Linux sqlite3 REPL.  Here's a sample session:

    SQLite version 2.6.0

     Enter "help" for usage hints

    sqlite> open Irises.db
    sqlite> select distinct species from irises
    ('Iris-setosa',)
    ('Iris-versicolor',)
    ('Iris-virginica',)
    sqlite> select species, avg(pet_len), avg(sep_len) from irises group by species
    ('Iris-setosa', 1.464, 5.005999999999999)
    ('Iris-versicolor', 4.26, 5.936)
    ('Iris-virginica', 5.552, 6.587999999999998)
    sqlite> select count(*) from irises
    (150,)
    sqlite> quit

It's not immediately obvious what benefits this provides over the existing sqlite-native repl and the python repl. Can you expand a bit on the use case?  Also, I seem to remember that Catherine Devlin had at one point thought about expanding her sqlpython to be multi-db capable, and while it doesn't look like that has happened, maybe that would be an alternative worth investigating?  (I've never used it or looked at its code, so it may not be.)

It could be added in Tools/scripts directory or as a part of the sqlite3 module.

> It's not immediately obvious what benefits this provides over the existing sqlite-native repl and the python repl.

The existing sqlite-native repl is not always installed when Python is installed (especially on Windows). It is handy that Python provides CLI to some modules, including zipfile and tarfile.

I would prefer CLI, but maybe both interfaces can be combined.

It would be nice to provide also a graphical Sqlite3 browser, which can be ran as a separate application and be integrated with IDLE (as turtledemo).

as a graphical sqlite browser, you have sqlite_bro that may give you inspiration. It's about one single file.

I think this is a good idea. Proof-of-concept implementation added (invoke REPL with `python -m sqlite3`).

Possible improvements:
- Use sqlite3.complete_statement()
- Support Python syntax as well. For example:
>>> select * from t
>>> res = _
>>> print(res[0])

Do we still want to do this? See https://discuss.python.org/t/titling-sqlite3-table-columns-with-number/13656/3.