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Separate PK in Jxn Tbl?



 
 
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  #221  
Old February 1st, 2008, 06:16 PM posted to comp.databases.ms-access, comp.databases.theory,microsoft.public.access, microsoft.public.access.tablesdbdesign,microsoft.public.sqlserver
Marshall[_3_]
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Posts: 20
Default Separate PK in Jxn Tbl?

On Jan 31, 4:59 pm, "Brian Selzer" wrote:

Constraints should always be checked by the DBMS, not by applications. If
you have two separate applications that manipulate the same table, and one
enforces one constraint while another enforces another, then all you need to
do to bypass one constraint is to use the other application! What, then, is
the point of even having the constraint?


I think that application constraints and database constraints are
really
two entirely separate things. The fact that they may be structurally
identical obscures and confuses this point. (Hence Brian's entirely
reasonable rhetorical question above.)

What, indeed, is the point of having one application and not another
enforce a constraint, *if we view this from the perspective of the
requirements of the database* Clearly there is none. However
individual applications may have requirements that are best
implemented as constraints *within the application.* I call these
"application constraints" because they are specific to the
application. They are *not* integrity constraints, even if we
are using identical mechanisms (in different locations) for both.


Marshall
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  #222  
Old February 1st, 2008, 07:52 PM posted to comp.databases.ms-access,comp.databases.theory,microsoft.public.access,microsoft.public.access.tablesdbdesign,microsoft.public.sqlserver
James A. Fortune
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Posts: 903
Default Separate PK in Jxn Tbl?

Marshall wrote:
On Jan 31, 4:59 pm, "Brian Selzer" wrote:

Constraints should always be checked by the DBMS, not by applications. If
you have two separate applications that manipulate the same table, and one
enforces one constraint while another enforces another, then all you need to
do to bypass one constraint is to use the other application! What, then, is
the point of even having the constraint?



I think that application constraints and database constraints are
really
two entirely separate things. The fact that they may be structurally
identical obscures and confuses this point. (Hence Brian's entirely
reasonable rhetorical question above.)

What, indeed, is the point of having one application and not another
enforce a constraint, *if we view this from the perspective of the
requirements of the database* Clearly there is none. However
individual applications may have requirements that are best
implemented as constraints *within the application.* I call these
"application constraints" because they are specific to the
application. They are *not* integrity constraints, even if we
are using identical mechanisms (in different locations) for both.


Marshall


I think you're on to something. Making a distinction between database
constraints and application constraints helps me clarify my thinking.
Being able to "reflect" database constraints to keep applications in
synch with changes sounds like a great idea.

James A. Fortune

  #223  
Old February 8th, 2008, 03:11 PM posted to comp.databases.ms-access,comp.databases.theory,microsoft.public.access,microsoft.public.access.tablesdbdesign
Gerry Hatrick[_2_]
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Posts: 2
Default Separate PK in Jxn Tbl?

"Frank Hamersley" wrote in message
...
Keith Wilby wrote:
"Frank Hamersley" wrote in message
...

provision of a menu option to reattach a data .mdb!


Is it just me or is that complete gibberish? Reattach?


Just you mate (at least I hope so or we are doomed).

Pray tell how do you distribute new versions of "code"?

Never had that concern? - always just hacked the live .mdb?

Gawd.


No, you have a development copy of the front end, there's no "reattaching"
of code, you just make a new version of the front end available - front end:
code and all other objects except the tables. Gawd, gibberish indeed.


 




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