Re: Field validation in DFU (Was: Thats all folks!)

Hello Rob,

You wrote:
>I didn't believe you so I had to check.  You're right, (I am not sure
>about always worked this way though).

Oh ye of little faith ...

>UPDDTA does support this.  However you can work around this with WRKDBF,
>(and probably other utilities).  However using check constraints would
>be better.  And would be enforced by WRKDBF and others.

True, but I don't see how you can hold the system responsible for the
shortcomings of another tool.  WRKDBF etc. could retrieve the validity
checks from the file and impose them in its displays but that's what
referential constraints and triggers are for.

>Since these constraints can be built into the SQL script to create a
>file, I argue that this would be better than having to rely upon a make
>utility to compile DDS and then add the constraints.

Putting constraints in the database is where they belong.  Anything else
leaves you open to some process bypassing the rules.  DDS is so much
older than SQL on the 400 so it's not surprising that SQL does things DDS
doesn't -- especially with Rochester's statement that some things will
never be implemented in DDS.  I don't agree with that direction but I can
understand it.

If you are creating new files then using SQL to define the files and
constraints is a good idea but if you have existing files then you must
add contraints after the fact.  At least with CHGPF support you no longer
lose any constraints when recompiling the DDS.

Regards,
Simon Coulter.
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