Re: Can these constraint be implemented in an RDBMS ?

On Tue, 2 Mar 2004 11:15:40 +0100, "ben brugman" <ben_at_niethier.nl> wrote:

>> There is a clear contradiction. Oracle and SQL-Server are not RDBMSs.
>
>Can you clearify this a bit more ?

Oracle and SQL Server are not truly Relational Database Management Systems, they violate The Relational Model in many ways.

>
>Can you name RDBMSs ?

No. I can't. They don't exist.

>Do you have a solution for the problem if this requirement (Oracle or
>SQL-server)
>is dropped.

It does not seem very difficult.

Here is a solution in Tutorial D I typed in a hurry and I have not checked, so I supose it is flawed O:-)

var Customers relation { Customer Char } key { Customer };

var Accounts relation { Account Char, Customer Char, Amount Numeric } key { Account };

var Sets relation { Set Char } key { Set };

var SetMinimums { Set Char, MinimunAmount Numeric }

    key { Set }
    foreign key { Set } references Set;

var SetAccounts { Set Char, Account Char }

    key { Set, Account }
    foreign key { Set } references Sets;

var IndividualAccounts view

    Accounts { Account } minus SetAccounts { Account };

var SetAccountsAmount view

    summarize SetAccounts join Accounts per SetAccounts { Set } add Sum(Amount) as Amount;

create constraint MaxAmount

    IsEmpty(Accounts where Amount > 100000000);

create constraint IndividualAccountsNotNegative

    IsEmpty((Accounts join IndividualAccounts) where Amount < 0);

create constraint SetAccountsNotNegative

    IsEmpty(SetAccountsAmount where Amount < 0);

create constraint MinimumAmount

    IsEmpty(SetAccountsAmount join SetMinimums where Amount < MinimumAmount);

> The imaginairy customer still likes to make a choice between at
>least two 'RDBMSs'.

Then he would have to build at least two RDBMSs by himself :)

Regards
  Alfredo Received on Tue Mar 02 2004 - 13:18:46 CET