DBKit: updating key fields

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2 total messages Started by & Garrett Tue, 28 Jul 1992 00:21

#268

Author: & Garrett
Date: Tue, 28 Jul 1992 00:21

21 lines
1562 bytes

It would appear that one can't update key fields.  When I change non-key  
fields and then save changes, the sybase table is updated correctly.  When  
I try to save changes that include changes for properties marked as key, I  
get "Error occured during transaction."
It would appear, quite simply, that DBKit builds the where clause of the  
update statement from the current (changed) values of the key fields  
rather than from their original values.
   - The key for this particular table is a five field key.  If I change  
my Model to make one of the key properties non-key, I can then update that  
field (as long as I don't change any of the remaining key fields, so it  
can still find the original row).
   - I can even edit _all_ the key fields so that the row has the same key  
as another row in the table, so that when I try to save I get "al_appt  
record has been modified in the database since the last fetch." instead.   
I think that's proof positive.

This is a complete disaster.  Any ideas?  Any knowledge of plans to fix  
this?

Colin Garrett
colin@delphi.bsd.uchicago.edu (NeXTMail)

Re: DBKit: updating key fields

#269

Author: Art Isbell
Date: Tue, 28 Jul 1992 02:53

15 lines
1318 bytes

Possibly, DBKit is trying to protect you from Sybase (and maybe many other
DBMS's).  Editting a key field is dangerous because Sybase implements an update
as a delete followed by an insert.  If the change you have made to a unique key
results in a duplicated key (another record with the same key exists), bye-bye
record.  The insert fails but the delete has already occurred!

So maybe the correct way to change a key is to insert a new record with the key
changed as you desire and if that succeeds, delete the previous record.
-- 

Art Isbell                                                      Cubic Solutions
NeXT Registered Developer #745         NeXT software development and consulting
Email: isbell@cats.UCSC.EDU                                Voice: (408)335-1154
USmail: 95018-9442                                           Fax: (408)335-2515

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