Re: Database and EO Modeller
Re: Database and EO Modeller
- Subject: Re: Database and EO Modeller
- From: Paul Lynch <email@hidden>
- Date: Tue, 4 Apr 2006 19:35:19 +0100
On 4 Apr 2006, at 19:13, David LeBer wrote:
On 4-Apr-06, at 1:58 PM, Jeffrey Pearson wrote:
Thanks to all (David and Paul) for the resource suggestions. I
ordered the books from Amazon...just a fyi: it was under $20 for
both of them!!!!
Also, I bought and have the videos. I have watched most of the
first one. Quick question. This app I am creating uses existing
data in an existing database. I was using straight java and jdbc
to connect and try to read from those table. After viewing the
video, it looks like I am going to be much happier if I copy off
the tables, use EOModeler to actually create the tables in the db
and then import the data. It looks like some invisible plumbing is
set up by using EOModeler to generate the database tables.
I don't think you will need to do this.
You really don't need to do this.
For most database structures, just do what David suggests and let
EOModeler give you your model. The only thing it adds, and this is
dependent on the driver, is the EO_PK_TABLE.
Now, there is something to be aware of, and this isn't explained too
well in the docs. EOF likes databases to follow it's own, mostly
undocumented, rules of good behaviour. There are ways around all of
these, but it helps to know the rules to start with.
Every table should have a primary key, and it will only automatically
manage keys if they are types it likes - numbers of any sort,
basically (plus some special cases). If you make a string field your
primary key, well, you can, but it's up to you to manage it.
When you create relationships, it only likes one-to-one relationships
where the foreign key is the primary key of the related table (which
is dumb, but it's an EOF rule).
I think those are the main expectations EOF has that don't conform to
common database design principles. Oh, and it works better (for
automatic creation of names, nothing major) if your table names are
singular, and not plural (so Person, not Persons).
Paul
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