I live the patch here for others:

original code shell $ which sqlite-utils | xargs cat ```python

!/usr/bin/python3

-- coding: utf-8 --

import re import sys from sqlite_utils.cli import cli

if name == 'main': sys.argv[0] = re.sub(r'(-script.pyw|.exe)?$', '', sys.argv[0]) sys.exit(cli()) ```

patched/sqlite-utils.py ```python

!/usr/bin/python3

-- coding: utf-8 --

import re import sys from sqlite_utils.cli import cli

New imports

from unittest.mock import patch from sqlite_utils.cli import VALID_COLUMN_TYPES

if name == 'main': # Choices of the option --type cli.commands['transform'].params[2].type.types[1].choices.append('DATETIME')

# The dicts has to be extended with a new type
with patch.dict('sqlite_utils.db.COLUMN_TYPE_MAPPING', {'DATETIME': 'DATETIME'}),\
     patch('sqlite_utils.cli.VALID_COLUMN_TYPES', VALID_COLUMN_TYPES + ("DATETIME", )):

    # Command is unchanged
    sys.argv[0] = re.sub(r'(-script\.pyw|\.exe)?$', '', sys.argv[0])
    sys.exit(cli())

```

And now it's working ```bash $ sqlite-utils schema events.sqlite cards.chunk.get CREATE TABLE "cards.chunk.get" ( [id] INTEGER PRIMARY KEY NOT NULL, [timestamp] TEXT, )

$ python patched/sqlite-utils.py transform events.sqlite cards.chunk.get --type timestamp DATETIME

$ sqlite-utils schema events.sqlite cards.chunk.get CREATE TABLE "cards.chunk.get" ( [id] INTEGER PRIMARY KEY NOT NULL, [timestamp] DATETIME, ) ```

lets users make schema changes, so it's important to me that the tool work in a non-surprising way -- if you ask for a column of type X, you should get type X. If the column or table previously had CHECK constraints, they shouldn't be silently removed

I've got your concern. Let's see if we will be replied on it and i'll close the issue some later.

Ah, it looks like that is controlled by this dict: https://github.com/simonw/sqlite-utils/blob/main/sqlite_utils/db.py#L178

I suspect you could overwrite the datetime entry to achieve what you want

And thank you for pointing me to it. At least, i can make a monkey patch for my need...

Isn't your suggestion too fundamental for the utility?

The bigger flexibility, the bigger complexity. Your idea make sense defenitely, but how often do you make schema changes? And how many people could benefit from it, what do you think?

Do you see a way to enable it without affecting existing users or bumping the major version number?

I don't see a clean solution, only extending code with a side variable that tells us we want to apply advanced types instead of basic.

it could be a similiar command like tranform-v2 --type column DATETIME or a cli option transform --adv-type column DATETIME along with a dict that contains the advanced types. Then with knowledge that we run an advanced command we take that dictionary somehow, we can wrap the current and new dictionaries by a superdict and work with it everywhere according to the knowledge. This way shouldn't affect users who are using the previous lib versions and it have to be merged in the next major one.

But this way looks a bad design, too messy.

I could, of course.

Doest it worth bringing such the improvement to the library?

That said, it looks like the check is only enforced at the CLI level. If you use the API directly, I think it'll work.

It works, but a column becomes TEXT

```python In [1]: import sqlite_utils In [2]: db = sqlite_utils.Database('events.sqlite') In [3]: table = db['cards.chunk.get'] In [4]: table.columns_dict Out[4]: {'id': int, 'timestamp': float, 'data_chunk_number': int, 'user_id': str, 'meta_duplication_source_id': int, 'context_sort_attribute': str, 'context_sort_order': str}

In [5]: from datetime import datetime In [7]: table.transform(types={'timestamp': datetime}) In [8]: table.columns_dict Out[8]: {'id': int, 'timestamp': str, 'data_chunk_number': int, 'user_id': str, 'meta_duplication_source_id': int, 'context_sort_attribute': str, 'context_sort_order': str} ```

bash ❯ sqlite-utils schema events.sqlite cards.chunk.get CREATE TABLE "cards.chunk.get" ( [id] INTEGER PRIMARY KEY NOT NULL, [timestamp] TEXT, ...

SQLite doesn't have a native DATETIME type. It stores dates internally as strings and then has functions to work with date-like strings. Yes it's weird.

That's correct. But my issue is about the application level libraries that, i suppose, have better data understanding if see a specific type such as DATETIME.

I'm writing data with dataset i've mentioned. The lib changes its behavior depending on a type. I saw different behavior with types DATETIME, FLOAT, TEXT. Dataset, for their part, is built upon Sqlalchemy, you know what it is.

To be honest, i didn't dive into the details of why the behavior changes, but when i altered manually by other util a type of column to DATETIME things got back to normal.

On the matter, can i achieve it with Sqlite Utils at the moment?