[Gambas-user] Problem with Gambas and MySql
Willy Raets
willy at ...2734...
Sat Oct 5 14:08:27 CEST 2013
On Sat, 2013-10-05 at 10:08 +0200, Fernando Martins wrote:
> On 10/05/2013 01:25 AM, Willy Raets wrote:
> > On Fri, 2013-10-04 at 22:53 +0200, Willy Raets wrote:
> >
> > Nando, Fernando and Caveat,
> >
> > Thanks for your responses.
> >
> >> Content in 'ICzakgewicht' can be like this:
> >> | ID | Gewicht |
> >> 345 100
> >> 345 100
> >> 345 50
> >> 347 200
> >> 347 200
> >> 347 200
> >> 347 200
> > @ Fernando and Caveat
> >
> > Above you can see that more than one record can be exactly the same.
> > At any time only one of them needs to be removed.
> > With Gambas this can be done, looking for the first record meeting the
> > criteria, delete it, next update and leave the table.
> >
> > With SQL DELETE all records that meet the criteria will be deleted
> > instead of only one.
> >
> > That is why this is not an option.
> >
> >
> "duplicate rows are and always were a mistake in SQL", C.J.Date
>
> http://books.google.nl/books?id=y_eVBB5qdwMC&pg=PA159&lpg=PA159&dq=c+j+date+duplicate+records&source=bl&ots=DjN-LDuU2B&sig=5-vlJ8itEkC7h6aFMt2PxHkT-ug&hl=en&sa=X&ei=1cdPUtjSCcHH0QWvooGQCw&redir_esc=y#v=onepage&q=c%20j%20date%20duplicate%20records&f=false
>
> In my experience, most often there is a design problem with the database
> allowing for duplicates. With duplicates, you step out of the set theory
> behind relational dbs and enter into trouble. I admit I have done it
> myself, but best be avoided.
>
Then adding a primary key should solve that problem.
--
Kind regards,
Willy (aka gbWilly)
http://gambasshowcase.org/
http://howtogambas.org
http://gambos.org
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