It would be really cool if you could register additional custom SQL functions for use with the sqlite-utils query command - something like this:

``` sqlite-utils data.db 'update images set domain = extract_domain(url)' --functions ' from urllib.parse import urlparse

def extract_domain(url): return urlparse(url).netloc ' ``` Every function defined in that code block would be registered with the connection, unless the name began with an underscore.

Suggested by @jefftriplett on Discord: https://discord.com/channels/823971286308356157/997738192360964156/1011655389063958600

Work in progress. Still needs documentation and tests (and to cover more cases of things that might have changed).

Refs: - #467

:books: Documentation preview :books:: https://sqlite-utils--468.org.readthedocs.build/en/468/

Interesting challenge with default_value: I need to be able to tell if the default values passed to .create() differ from those in the database already.

Introspecting that is a bit tricky:

```pycon

import sqlite_utils db = sqlite_utils.Database(memory=True) db["blah"].create({"id": int, "name": str}, not_null=("name",), defaults={"name": "bob"}) <Table blah (id, name)> db["blah"].columns [Column(cid=0, name='id', type='INTEGER', notnull=0, default_value=None, is_pk=0), Column(cid=1, name='name', type='TEXT', notnull=1, default_value="'bob'", is_pk=0)] `` Note how a default value of the Python stringbobis represented in the results ofPRAGMA table_info()asdefault_value="'bob'"` - it's got single quotes added to it!

So comparing default values from introspecting the database needs me to first parse that syntax. This may require a new table introspection method.

Originally posted by @simonw in https://github.com/simonw/sqlite-utils/issues/468#issuecomment-1229279539

I've run into an issue with extract and I don't believe this is the intended behaviour.

I'm working with a database with music listening information. Currently it has one large table listens that contains all information. I'm trying to normalize the database by extracting relevant columns to separate tables (artists, tracks, albums). Not every track has an album.

A simplified demonstration with just track_title and album_title columns: ```ipython In [1]: import sqlite_utils

In [2]: db = sqlite_utils.Database(memory=True)

In [3]: db["listens"].insert_all([ ...: {"id": 1, "track_title": "foo", "album_title": "bar"}, ...: {"id": 2, "track_title": "baz", "album_title": None} ...: ], pk="id") Out[3]: <Table listens (id, track_title, album_title)> ```

The track in the first row has an album, the second track doesn't. Now I extract album information into a separate column: ```ipython In [4]: db["listens"].extract(columns=["album_title"], table="albums", fk_column="album_id") Out[4]: <Table listens (id, track_title, album_id)>

In [5]: list(db["albums"].rows) Out[5]: [{'id': 1, 'album_title': 'bar'}, {'id': 2, 'album_title': None}]

In [6]: list(db["listens"].rows) Out[6]: [{'id': 1, 'track_title': 'foo', 'album_id': 1}, {'id': 2, 'track_title': 'baz', 'album_id': None}] ```

This behaves as expected -- the album table contains entries for both the existing album and the NULL album. The listens table has a foreign key only for the first row (since the album in the second row was empty).

Now I want to extract the track information as well. Album information belongs to the track so I want to extract both columns to a new table. ```ipython In [7]: db["listens"].extract(columns=["track_title", "album_id"], table="tracks", fk_column="track_id") Out[7]: <Table listens (id, track_id)>

In [8]: list(db["tracks"].rows) Out[8]: [{'id': 1, 'track_title': 'foo', 'album_id': 1}, {'id': 2, 'track_title': 'baz', 'album_id': None}]

In [9]: list(db["listens"].rows) Out[9]: [{'id': 1, 'track_id': 1}, {'id': 2, 'track_id': None}] ```

Extracting to the tracks table worked fine (both tracks are present with correct columns). However, the listens table only has a foreign key to the newly created tracks for the first row, the foreign key in the second row is NULL.

Changing the order of extracts doesn't help.

I poked around in the source a bit and I believe this line (essentially comparing NULL = NULL) is the problem, but I don't know enough about SQL to create a reliable fix myself.

sqlite "IS" is equivalent to SQL "IS NOT DISTINCT FROM"

closes #423

Refs #470

:books: Documentation preview :books:: https://sqlite-utils--473.org.readthedocs.build/en/473/

Imitate: - https://github.com/simonw/datasette/pull/1789 ```

would load default entrypoint like before

datasette data.db --load-extension ext

loads the extensions with the "sqlite3_foo_init" entrpoint

datasette data.db --load-extension ext:sqlite3_foo_init

loads the extensions with the "sqlite3_bar_init" entrpoint

datasette data.db --load-extension ext:sqlite3_bar_init ```

I figured out a workaround for the ugly global x hack here: - https://github.com/simonw/sqlite-utils/issues/471#issuecomment-1229120653

For consistency with search: https://sqlite-utils.datasette.io/en/stable/cli-reference.html#search

-o, --order TEXT Order by ('column' or 'column desc')

I wanted to run sqlite-utils rows db.db mytable --order 'rowid desc' to see the most recently imported rows.