Thread: [Haskelldb-users] Exception: No match in record selector Database.HaskellDB.Sql.attrs

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Hi all,

I get this error

Exception: No match in record selector Database.HaskellDB.Sql.attrs

in some cases when I do union, intersection or minus.

What does that mean?

Günther

I don't see a place in the source where that exception is thrown
(grepping for variations on the error string didn't give me anything).
 Are you sure it's HaskellDB?

On Wed, Apr 15, 2009 at 8:17 AM, Guenther Schmidt <gue...@we...> wrote:
> Hi all,
>
> I get this error
>
> Exception: No match in record selector Database.HaskellDB.Sql.attrs
>
> in some cases when I do union, intersection or minus.
>
> What does that mean?
>
> Günther
>
>
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Hi Justin,

the explanation, I believe, is found here: 
http://www.haskell.org/ghc/docs/latest/html/libraries/base/Control-Exception.html#t%3ARecSelError

I'm just wondering what I did that would eventually cause it in the 
first place.

Quite possible I construct my code, ie the Query (Rel whatever) in a 
way, or in an order, that does compile but throws a runtime error 
nevertheless.

I'm using ghc 6.10.

Would you happen to have some brief example of how to do intersect, 
union or minus properly?

Günther

Justin Bailey schrieb:
> I don't see a place in the source where that exception is thrown
> (grepping for variations on the error string didn't give me anything).
>  Are you sure it's HaskellDB?
>
> On Wed, Apr 15, 2009 at 8:17 AM, Guenther Schmidt <gue...@we...> wrote:
>   
>> Hi all,
>>
>> I get this error
>>
>> Exception: No match in record selector Database.HaskellDB.Sql.attrs
>>
>> in some cases when I do union, intersection or minus.
>>
>> What does that mean?
>>
>> Günther
>>
>>
>> ------------------------------------------------------------------------------
>> This SF.net email is sponsored by:
>> High Quality Requirements in a Collaborative Environment.
>> Download a free trial of Rational Requirements Composer Now!
>> http://p.sf.net/sfu/www-ibm-com
>> _______________________________________________
>> Haskelldb-users mailing list
>> Has...@li...
>> https://lists.sourceforge.net/lists/listinfo/haskelldb-users
>>
>>     

On Wed, Apr 15, 2009 at 8:58 AM, Guenther Schmidt <gue...@we...> wrote:
> I'm just wondering what I did that would eventually cause it in the first
> place.
>

Ah, I see now. If you look at Sql.hs, you can see attrs is defined as
a selector function on SqlSelect values. If attrs is applied to some
other value of that type (SqlBin, for example), then you would see
this error. I suspect it's a bug and if you can isolate it  (with
dummy table definitions) that would help a lot.

> Would you happen to have some brief example of how to do intersect, union or
> minus properly?
>

I don't unfortunately.

Justin

Hi all,

I'm trying to debug the program, so I copied the haskelldb modules (the 
database directory) to a location within my app in order for my app to 
use the interpreted code.

However ghci complains about some extensions missing and I can't figure 
out which particular ones those are.

Günther