Re: new subscriber, not sure how to post my query to your list

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On Tue, Apr 24, 2012 at 6:38 PM, Leon <leonpaul2 gmail com> wrote:

Have just subscribed to your Dia-mail list, but am having trouble finding ou thow to post a help request on Dial mailing list.

Grateful if you can insert the following post for me, or advise.  Thanks

"Have not designed a db since days of Access2, so very rusty. Am now considering using 'Base' in LO/HSQLDBv2.  Am a newbie to both UML, Dia, and Base/HSQL!   I remember with Access, I created my tables, and THEN created an ERD diagram automatically from the design.    I guess logically the ERD should come first, and the table creation and links flow from that.  So as OOo/LO dont appear to be able to Create a ERD, and I saw a reference in OOo documentation recommending Dia, have been trying to use it.    I successfully used Dia .972 to draw all the Classes I need, but am a bit unsure HOW to create the correct links.

1)  My Access generated ERD's had only 1 type of link: lines between table ID's with arrow symbol at FK end, no symbol at PK end.  As I rcall, the textbooks of the day used the same symbol - often with a 1:n at the FK end.  Dia-UML has a slection of link symbols.  Should I use the UML-Generalisation tool, or the UML-Aggregation tool to create the typical 1:n & other relations ?

2)  When dragging a link towards a key in a class ( to make a relation between 2 classes) I noticed when the 'handle' reached the border of the Class, the shape turns 'red' - so I assumed it had connected (as per Dia.Manual 4.2.5).  After creating many more links, I inadvertantly dragged the 'handle' further into the Class box, and noticed the shape turns 'yellow' - no ref. in Dia.Manual

I would like an explanation of the difference between the 'Red' and 'yellow' signals, and which should I use.

3)  Once the ERD is complete, what current tools are there to a) report on its correctness, and b) use it to generate the tables and links in LO/HSQLDB-V2 ?  My platform is Windows7. I saw a quite old guide using 'tedia2SQL' to create SQL statements. However, the tedia2sql site states it no longer works as the Dia file format has changed.  Also, I think the guide used linux and it was not clear if tedia2sql worked in a simple Windows7 platform.

A minor question using Dia is:  In case I later want to Edit the name or type of a field (used in many Classes) is it safe to save the .dia uncompressed, then use 'Notepad' to do a global 'Replace' ?

I am also very much a newbie with SQL.  For some very small lookup tables I would like to use a 'tinyint' as an auto-incrementing id for new entries.  All examples seem to use 'Int'.  Any reason I can't use tinyint ?

I apologise for asking such basic questions and will be very grateful if you can help me through this initial phase with using Dia for front-ending a Database design."

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