De: David G. Johnston <david.g.johns...@gmail.com>
Enviada: 11 de maio de 2025 01:58
ALTER TABLE table_name
ADD CONSTRAINT constraint_name
CHECK (condition)
MESSAGE 'Custom error message when the condition is not met.';
>> I’m seeing some value here but, odds are, there is not enough obvious
>> benefit or design to convince someone else to try and envision specifically
>> how the behavior should work and effort to push it through.
if I have to use a trigger to set a different message, then I have to write the
same rule twice, in CHECK and TRIGGER, which is redundant.
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Improved User Experience: Applications could capture and display more
contextual and helpful error messages to end-users, improving usability and
reducing confusion.
>> Arguably a layering violation. To make this point more clearly, do you need
>> to account for i18n?
No
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Enhanced Debugging: Developers could immediately identify the specific
business rule that has been violated, speeding up the debugging and resolution
of data integrity issues.
>> Is there really a meaningful gap here?
I think there is a significant gap here, especially in complex constraints. The
constraint name does not always reveal which specific part of the business rule
was violated, which can delay debugging. Personalized messages could provide
this information directly
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Implicit Documentation: The custom message would serve as a way to document
the intent of the constraint directly within the database schema, facilitating
understanding and maintenance of the data model.
>> Constraints can be targeted by “comment on”.
I agree, but the proposal aims at specific error messages when the constraint
is violated, for better feedback in development and in applications.
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Consistency: It would allow for a more consistent approach to providing
informative feedback on business rule violations, complementing the existing
capability in triggers.
Two different tools that can do the same job. One with structure and one
customizable. Because triggers exist the proposed feature is less useful.
Best regards,
Miguel Ferreira
