haskelldb-users

[Haskelldb-users] Another try

[Immanuel N. <i.n...@ja...>]

Hello,

this is another try to get help about a question which I have send to
this mailing list about 2 weeks ago under the subject "Missing SQL
features". I haven't received any feedback may be because the traffic is
rather low in this mailing list - so I try again:

I can't find the SQL operators exists (and join) in HaskellDB. Are they
not supported yet or have they different names here?

Basically I need to express in HaskellDB something like:

SELECT DISTINCT store_type FROM stores
  WHERE NOT EXISTS (SELECT * FROM cities_stores
                    WHERE cities_stores.store_type = stores.store_type);

(i.e. asking the question "What kind of store is present in no cities?")

Any hints how to accomplish this in HaskellDB are highly appreciated.

Thanks,
Immanuel

Re: [Haskelldb-users] Another try

[Bjorn B. <bri...@cs...>]

On Nov 20, 2007, at 11:05 , Immanuel Normann wrote:

> Hello,
>
> this is another try to get help about a question which I have send to
> this mailing list about 2 weeks ago under the subject "Missing SQL
> features". I haven't received any feedback may be because the =20
> traffic is
> rather low in this mailing list - so I try again:
>
> I can't find the SQL operators exists (and join) in HaskellDB. Are =20
> they
> not supported yet or have they different names here?
>
> Basically I need to express in HaskellDB something like:
>
> SELECT DISTINCT store_type FROM stores
>   WHERE NOT EXISTS (SELECT * FROM cities_stores
>                     WHERE cities_stores.store_type =3D =20
> stores.store_type);
>
> (i.e. asking the question "What kind of store is present in no =20
> cities?")
>
> Any hints how to accomplish this in HaskellDB are highly appreciated.
>
> Thanks,
> Immanuel

Hi Immanuel,

EXISTS is unfortunately not implemented yet. There are only inner =20
joins. Fixing these deficiencies would be very welcome.

/Bj=F6rn

Re: [Haskelldb-users] Another try

[Immanuel N. <i.n...@ja...>]

On Tue, 2007-11-20 at 11:40 +0100, Bjorn Bringert wrote:

> EXISTS is unfortunately not implemented yet. There are only inner  
> joins. Fixing these deficiencies would be very welcome.

I will have a look at it - as soon as I am relieved from other dominant
dueties.

Still I couldn't find even inner joins in the haskellDB 0.10 API.

Immanuel

Re: [Haskelldb-users] Another try

[Bjorn B. <bri...@cs...>]

On Nov 20, 2007, at 11:55 , Immanuel Normann wrote:

> On Tue, 2007-11-20 at 11:40 +0100, Bjorn Bringert wrote:
>
>> EXISTS is unfortunately not implemented yet. There are only inner
>> joins. Fixing these deficiencies would be very welcome.
>
> I will have a look at it - as soon as I am relieved from other =20
> dominant
> dueties.
>
> Still I couldn't find even inner joins in the haskellDB 0.10 API.
>
> Immanuel

Inner joins are implicit. Using two 'table' calls makes a cartesian =20
product between those tables. You can then use 'restrict' with =20
equality on fields from the two tables to get an equi-join.

/Bj=F6rn