[Ur] SQL table.field IN list

[Artyom Shalkhakov]

Hi Simon,

сб, 12 янв. 2019 г. в 16:15, Simon Van Casteren <simon.van.casteren at gmail.com>:
>
> Hi,
>
> Am I correct in thinking that the standard library/compiler doesn't support SQL "IN" statements? It's something that I use a lot in my programs, and in psql for example you can just do:
>
> SELECT *
> FROM uw_lesson_lessons
> WHERE uw_id in (1, 2, 3)
>

Yes, it doesn't seem to be supported at the moment.

> I made my own function to handle this, using a bunch of sql_or statements:
>
> fun inlist
>       [a ::: Type]
>       [otherfields ::: {Type}]
>       [tablename :: Name]
>       [columnname :: Name]
>       [otherfields ~ [columnname = a]]
>       (_ : sql_injectable a)
>       (ids: list a)
>     : sql_exp ([tablename = [columnname = a] ++ otherfields]) ([]) ([]) bool
>   =
>   List.foldl
>     (fn id acc => (SQL {acc} OR {{tablename}}.{columnname} = {[id]}))
>     (WHERE {[False]})
>     ids
>
> I'm not sure about the performance characteristics of this though. Anyway, just wondering if it is already supported but I can't find it, or it's not supported at all?
>

Well I think you should really file an issue for this on GitHub. I'd
like to work on it but it seems that it would require extending
Ur/Web's grammar, then adding some way to handle the right-hand side
of the operator -- which is an SQL tuple (right?), and we don't have
those in the syntax elsewhere except the INSERT clause handling. This
is a bit too much for my ability right now.

Other than that, I'm really in favor of adding it.

> Thanks
>
> Simon
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-- 
Cheers,
Artyom Shalkhakov