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From Jakob Braeuchi <jbraeu...@gmx.ch>
Subject Re: PersistenceBroker.getCount() -- Doesn't work for MSSQL Uniqueidentifiers!!!
Date Sat, 24 Jan 2004 15:13:00 GMT
hi andrew,

according to some newsgroups there's no performance penalty for using count(*) 
instead of count(pk). so we could use count(*) for queries not using DISTINCT.

i'll have a look at it asap.

hth
jakob

Clute, Andrew wrote:

> The getCount function does a 'select count(<pk>)' where it inserts the
> primary keys for your return class into the count clause.
> 
> That is great, until you are using, like we are, a field of type
> 'uniqueidentifier' that is available in SQL 7 and up. MSSQL Server does
> not support that using of uniqueidentifier's as the clause for a count.
> You will get the following error:
> 
> 'The count aggregate operation cannot take a uniqueidentifier data type
> as an argument.'
> 
> So, this leaves me in a bad position -- by using that as my primary key,
> I can no longer access length's of my result set (and secondary be able
> to do paging).
> 
> I don't see any workaround in the current code, and am wondering if
> there is an appropriate fix for this problem for the codebase?
> 
> Is there a reason why we couldn't have the ability to do 'select
> count(*)' as a fallback?
> 
> I will admit, I don't know the intricate details about SQL92 -- so I
> don't know what the benefit of naming a column in a count clause versus
> the '*'.
> 
> I guess my other solution is to extend PersistenceBroker and make my own
> implementation for that, and not use the pk's in the count clause (what
> would the side effects be of that)?
> 
> Thanks
> 
> -Andrew
> 
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