Re: Why all the max length constraints?

dawn wrote:

>
> In SQL-DBMS's, like VSAM (and other indexed sequential files before
> them) a lot of attributes are specified with max length constraints.
> While there are some attributes where this constraint is related to a
> conceptual constraint (from the analysis phase), these lengths are
> often introduced for the logical model or implemenation in the DBMS.
>

I think the question is clear enough, are fixed-length fields an intrinsic requirement of the relational model?

Short answer: no.

But they are such a pervasive element of implemented systems that they may appear to be a requirement, like the SQL language itself.

Going further, fixed widths are indefensible. RM seeks to separate implemention details from data handling, therefore a fundamentalist mindset would sooner or later fix on fixed-width fields as heretical.

-- 
Kenneth Downs
Secure Data Software, Inc.
(Ken)nneth_at_(Sec)ure(Dat)a(.com)