Re: Accuracer C/S Database?

From: Hannes Danzl (hannes_at_nexusdb.dbnexus.com)
Date: 12/13/04 

Date: 13 Dec 2004 11:19:57 -0800

Hello Alex,

> I don't think the data dictionary in NXDB is the same as the one in
> Advantage. The data dictionary in Advantage contains the meta data of
> the database including the declaration of the referential integrity
> (RI), stored procedure, views, users, user groups and database object
> permissions including column level permissions, just to name a few off
> the top of my head.

i think they are very similar in concept. nexusdb also stores the complete
definition of a table in it's datadict. that not only includes fields, indices,
.. but also default value, validation, RI, FileEngine, RecordEngine, Encryption,
Compression descriptors (which define which engine to use for reading the
actual records). Essentially everything that is associated with "managing"
the table file.

> Correct me if I am wrong, but I read that the RI in NXDB is only a
> proof of concept. It is very different from the way Oracle, SQL-Server
> or Advantage's RI. You cannot declare an RI in NXDB. You have to
> program it in code and re-compile the server. I am not sure about the
> re-compiling the server part but I am certain about the programming
> part.

it's not a proof of concept. it didn't make it into the initial release and
since the changes would break the dictionary of older databases we added
it as a bonus. that's the reason for the need to recompile the server, because
you need to add *one* uses clause. you're right that in V1 there's no graphical
tool to define the RI constraints, you need to add them by code to the data
dictionary.

> Can NXDB use expressions such as Today(), Now() as default values to
> timestamp a record?

via the datadictionary and via sql (not full support in V1 but in V2) yes.

> How about PHP, DBI and JDBC driver :)

PHP module is there, JDBC only over odbc bridge, DBI no. 

--
  Hannes Danzl (hannes@nexusdb.dbnexus.com)
  Nexus Database Systems Pty Ltd
  (please remove the .dbnexus in the email to answer direcly)

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