Help with creating DB

I have created a sample db :

http://communities.bentley.com/members/Jerry-Walter-_2D00_-Bentley/files/sample.mdb.aspx

As for the anology with Excel, look at the db this way :

The sheet tab in Excel is the same as the table in the db.

The row in Excel sio the same as a record in the db table.

The column in Excel is the same as a field (column) in the  db table.

HTH

Jerry

Hi Maciej,

if you work with Power Map V8i, there is a question where is the best to store the non-graphical information (attributes). As you wrote your can attach an external database to elements but you can also create XFM project and to store the information directly in DGN file. Both ways have own pros and cons, so you should to think how the data will be used.

In my opinion XFM project is a more complex way, but better in longer perspective as you don't have to maintain "sychronization" between DGN and DB. But the question is also how many object you work with etc.

WIth regards,

 Jan

Hi,

whell te inpt number of light pionts is around 3800 and also there are some control cabineta as well as a stering and supply lines that have to be characterised. So I think in total there can be up to 10000 elements.

Can you tell me some more thing about XFM?? I never heard about it before.

MaciejG said:

Can you tell me some more thing about XFM?

Hmm ... not easy request, because XFM is complex technical topic, there are information available at Bentley site already. But let's do simple short (which means not precise in some aspects) introduction :-)

There are two important "questions" related to GIS on Bentley platform:

• Where are attributes stored (expected graphics is in DGN file): In external database or internally in DGN.
  External database (from Access mdb to Oracel and SQL Server etc.) is a traditional way in MicroStation, where connection is realized using mslink and entity number information stored with graphical element. If more people use DGN and/or the database, a problem is how to maintain synchronization between them - what will happen if somebody delete element or database row. Despite of this technology is very old, it works fine and is simple.
  In DGN file the data can be stored in several different ways. You probably know tags, but there are also XML fragments (technology used by Bentley Map to version V8i (SELECTseries 2)) and XAttributes (used by Bentley Map from V8i (SELECTseries 3)). In some cases a disadvantage is the data cannot be accessed by a different tool than Bentley Map (comparing to standardized SQL access to external databases).
• How GIS project is defined. If you work with non-graphical data, new questions and challenges appear: How to define user interface to enter data, how to check what is entered, how to manage the whole project etc. The optimal solution is if the things are not hard-coded into a product, but the project can be defined using some tool.

What is XFM project?
It's technology, which is the base of Bentley Map and it provides answer to both mentioned questions:

• By default all data (graphics + attrbiutes) are stored in DGN file(s), but you can also set, that a specific property is stored in an external database. In such case the "old good" mslink is used.
• The whole project (features, their symbology and properties, methods and operations, GUI etc.) is defined using Bentley Geospatial Administrator. The result is Bentley Map workspace, which in fact is normal MicroStation workspace plus a set of XML configuration files, that describe all aspects of the project.

I can imagine a project with several DGNs (it's not a good idea to store nearly 4000 features in one DGN), where the property (attributes) you mentioned willbe stored in DGN file also. But it require at least short analysis and more information to make a correct decision.

I hope it will help you,

  Jan

There are excellent courses offered by the Bentley Institute for this very subject. Please lookup the "Bentley Map Administrator" course at

learn.bentley.com/.../Public