issues: 1227571375

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id node_id number title user state locked assignee milestone comments created_at updated_at closed_at author_association pull_request body repo type active_lock_reason performed_via_github_app reactions draft state_reason
1227571375 I_kwDOCGYnMM5JK0Cv 431 Allow making m2m relation of a table to itself 738408 open 0     3 2022-05-06T08:30:43Z 2022-06-23T14:12:51Z   NONE  

I am building a database, in which one of the tables has a many-to-many relationship to itself. As far as I can see, this is not (yet) possible using .m2m() in sqlite-utils. This may be a bit of a niche use case, so feel free to close this issue if you feel it would introduce too much complexity compared to the benefits.

Example: suppose I have a table of people, and I want to store the information that John and Mary have two children, Michael and Suzy. It would be neat if I could do something like this:

```python from sqlite_utils import Database

db = Database(memory=True) db["people"].insert({"name": "John"}, pk="name").m2m( "people", [{"name": "Michael"}, {"name": "Suzy"}], m2m_table="parent_child", pk="name" ) db["people"].insert({"name": "Mary"}, pk="name").m2m( "people", [{"name": "Michael"}, {"name": "Suzy"}], m2m_table="parent_child", pk="name" ) ```

But if I do that, the many-to-many table parent_child has only one column: CREATE TABLE [parent_child] ( [people_id] TEXT REFERENCES [people]([name]), PRIMARY KEY ([people_id], [people_id]) )

This could be solved by adding one or two keyword_arguments to .m2m(), e.g. .m2m(..., left_name=None, right_name=None) or .m2m(..., names=(None, None)).

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