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
326800219,MDU6SXNzdWUzMjY4MDAyMTk=,292,Mechanism for customizing the SQL used to select specific columns in the table view,9599,closed,0,,,15,2018-05-27T09:05:52Z,2021-05-27T04:25:01Z,2021-05-27T04:25:01Z,OWNER,,"Some columns don't make a lot of sense in their default representation - binary blobs such as SpatiaLite geometries for example, or lengthy columns that really should be truncated somehow.

We may also find that there are tables where we don't want to show all of the columns - so a mechanism to select a subset of columns would be nice.

I think there are two features here:

* the ability to request a subset of columns on the table view
* the ability to override the SQL for a specific column and/or add extra columns - `AsGeoJSON(Geometry)` for example

Both features should be available via both querystring arguments and in `metadata.json`

The querystring argument for custom SQL should only work if `allow_sql` config is turned on.

Refs #276",107914493,issue,,,"{""url"": ""https://api.github.com/repos/simonw/datasette/issues/292/reactions"", ""total_count"": 2, ""+1"": 2, ""-1"": 0, ""laugh"": 0, ""hooray"": 0, ""confused"": 0, ""heart"": 0, ""rocket"": 0, ""eyes"": 0}",,completed