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
743384829,MDExOlB1bGxSZXF1ZXN0NTIxMjg3OTk0,203,changes to allow for compound foreign keys,1049910,open,0,,,7,2020-11-16T00:30:10Z,2023-01-25T18:47:18Z,,FIRST_TIME_CONTRIBUTOR,simonw/sqlite-utils/pulls/203,"Add support for compound foreign keys, as per issue #117 

Not sure if this is the right approach. In particular I'm unsure about:

 - the new `ForeignKey` class, which replaces the namedtuple in order to ensure that `column` and `other_column` are forced into tuples. The class does the job, but doesn't feel very elegant.
 - I haven't rewritten `guess_foreign_table` to take account of multiple columns, so it just checks for the first column in the foreign key definition. This isn't ideal.
 - I haven't added any ability to the CLI to add compound foreign keys, it's only in the python API at the moment.

The PR also contains a minor related change that columns and tables are always quoted in foreign key definitions.",140912432,pull,,,"{""url"": ""https://api.github.com/repos/simonw/sqlite-utils/issues/203/reactions"", ""total_count"": 1, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 1, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",0,
1555701851,PR_kwDOBm6k_c5IdsD7,2003,Show referring tables and rows when the referring foreign key is compound,536941,open,0,,,3,2023-01-24T21:31:31Z,2023-01-25T18:44:42Z,,CONTRIBUTOR,simonw/datasette/pulls/2003,"sqlite foreign keys can be compound, but that is not as well supported by datasette as single column foreign keys.

in particular, 

1. in a table view, there is not a link from the row to the referenced row if the foreign key is compound
2. in a row view, there is no listing of tables and rows that refer to the focal row if those referencing foreign keys are compound.

Both of these issues are discussed in #1099. 

This PR only fixes the second one, because it's not clear what the right UX is for the first issue.

![Screenshot 2023-01-24 at 19-47-40 nlrb bargaining_unit](https://user-images.githubusercontent.com/536941/214454749-d53deead-4151-4329-a5d4-8a7a454de7d3.png)

Some things that might not be desirable about this approach.

1. it changes the external API, by changing `column` => `columns` and `other_column` => `other_columns` (see inline comment for more discussion.
2. There are various places where the plural foreign keys have to be checked for length and discarded or transformed to singular. 
",107914493,pull,,,"{""url"": ""https://api.github.com/repos/simonw/datasette/issues/2003/reactions"", ""total_count"": 0, ""+1"": 0, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",0,