The Rel Forum

I downloaded Relinstall-1.0.10.jar and installed it.
When I try to launch DBrowser or Rel I get
Unable to access jarfile DBrowser.jar
Unable to access jarfile Rel.jar

I'm running OS 10.6.8, and I checked Software Update.
java -version shows me
java version "1.6.0_65"

acc to java.com:
Mac OS X Version 10.6 and below
Use Software Update available on the Apple menu to check that you have the most up-to-date version of Java 6 for your Mac. Java 7 is not supported by these older versions of Mac OS X.

Is there a DBrowser.jar and Rel.jar in the installation folder?

If both DBrowser.jar and Rel.jar are present, try launching DBrowser.jar

Thanks, yes it opens now.
(I had been trying to do it from command line.)
Greatly appreciate your efforts to help us do relational right, so to speak.

Can you help me get started creating relation variables and relations using Rel? I'm experimenting with MySQL for my purposes, but would prefer if I can accomplish the same with a truly relational tool.
In the past, I went through Date's An Introduction to Database Systems, 7th edition in its entirety, applying it in conjunction with work where I was creating relations, forms, reports based on queries I wrote directly in SQL, using an off-the-shelf DBMS.
In the references I've looked at from Date's book and your home page, I'm still searching for a presentation of what Tutorial D uses in place of something like this:

CREATE TABLE ExampleTable
(
ID int PRIMARY KEY,
FirstName varchar(16) NOT NULL,
LastName varchar(16) NOT NULL,
BirthDate date NOT NULL
);

and this:

INSERT INTO ExampleTable (ID, FirstName, LastName, BirthDate)
VALUES (1, 'John', 'Doe', '1970-01-01'), (2, 'Jane', 'Doe', '1970-01-02');

For links to documentation on Tutorial D, look under the Documentation heading on Rel's home page at http://dbappbuilder.sourceforge.net/ The Database Explorations: Essays on The Third Manifesto and related topics book or Hugh Darwen's Exercises on Relational Database Theory e-book at http://bookboon.com/en/exercises-on-rel ... eory-ebook are excellent sources.

Your first example would be: The above assumes the existence of a DATE type, which you'd need to define or load because it's not a built-in type. If you just want to try it quickly, replace DATE with (say) CHAR.

To insert: If you've defined BirthDate as a CHAR type, then replace BirthDate DATE('1970-01-02') with BirthDate '1970-01-02'.

Next questions I haven't found an answer to are:

• how to use the Location bar in DBrowser (it seems give me the same results, e.g. query to display a relation does so the same, no matter what I put in the Location bar)
  how to actually locate the files I've created on my hard drive
  how to actually "Open Local Database" (from the (...) button) -- e.g. it won't open a .csv file, and I can't find relations I have created in DBrowser at all in the file system

The location specifies the directory that contains a database. For example, on my machine, if I create a new folder called MyDatabase in /home/dave/MyDatabase, and specify local:/home/dave/MyDatabase in the Rel DBrowser Location, it will create a database in the MyDatabase folder. When I want to open it later, I can specify local:/home/dave/MyDatabase in the Location. You can also use the File menu to browse to the database folder you want to open or create, and it will automatically fill in the Location.

It won't open a CSV file because a CSV file isn't a Rel database. One of my students has created a set of Rel extensions for accessing CSV files, Excel spreadsheets and so on, but that won't be available until the next update.

Rel uses its own format for databases, so relations are not accessible via the filesystem.

For Web development purposes:
Can I place a Rel database on my Web host?
and access it via Web pages using something like php or python?
Or will I have to fall back on a DBMS like MySQL for the time being?

In principle you can, but it might not be as easy as you'd like. You can easily run a Rel server on your Web host, but as there is no ODBC or JDBC driver (yet!) for Rel, you would either have to use Berkeley sockets from within PHP or Python to communicate with the Rel server, or use the Rel3Client Java API implemented in relclient.jar.