MartyConnelly
martyconnelly at shaw.ca
Tue Mar 28 17:31:12 CST 2006
Here is one starting point, it is a library of 4 or 5 hundred simple data models plus a simple tutorial. Handy if you need something to show a client in half an hour as a starting discussion point. Some can be used as sub-models http://www.databaseanswers.org/data_models/index.htm Some samples have a conceptual model, physical data model and or business rules Some also have an emailable Access mdb. Sample business rules http://www.databaseanswers.org/data_models/airline_booking/facts.htm For re-engineering or design, I use a CASE tool, most are in the $99 range, some go for thousands. The one I prefer for Access SQL Server work is Enterprise Architect http://www.sparxsystems.com.au/ea.htm or some of these http://www.databaseanswers.org/modelling_tools.htm The guy that runs this site prefers Dezign http://www.datanamic.com/ Shamil Salakhetdinov wrote: >Hi All, > >I wanted to ask you how do you usually try to quickly understand existing >real life applications data models? > >I mean the following: > >- imagine you've got a task to program some utility code for an application >with rather tricky datamodel, working application and the question to change >this tricky datamodel is out of your responsibility - you're not allowed >even to discuss this question (I'm exaggerating about that latter - just >wanted to outline that your task is to understand the existing datamodel >whatever it's as quickly as possible, accept it and to deliver your solution >in time and as good as possible in the given context because the customer is >waiting for your working solution not your considerations about datamodel >and how good it could have been if you have been allowed to change it....). > >- there is a good description of this datamodel and its business area but to >program effectively you can use just a subset of this datamodel and its >description, which you need to quickly filter out from all the existing >(thick) stuff to make a simple submodel diagram of the tables used in your >utilities and their relationships. And you do not want to spend time to >understand all the rest of this datamodel because you're more interested to >go watching the next series of Dexter and DeeDee or watch the 100th time >your favorite action movie like I do sometimes watch "The White Sun of >Desert" - a famous here Soviet action movie I first time watched in 1969 >:)... > >The question is how to quickly understand such a data model and to get it >well arranged to solve the urgent customer task? (You given the datamodel >diagram but relationships are intersected in a tricky net) > >Did you ever try to solve such a task first of all on an abstract level? I >mean did you ever try to "play" with existing datamodel relationships >diagram (graphical diagram I mean) without knowing(/without even taking into >account) the meanings(titles) of the tables and their relationships? With >the main purpose of this playing being to finally get a relationships >structure(graphical diagram) clearly showing you what are the key points of >this datamodel, what a the "juncture points", what are the "bands and >whistles"? > >I did try and I think it always work for tricky, sometimes not optimal but >rather well normalized data model. > >I think this is called "building star schema abstract method". >And it works in most of the cases. >Try it. > >I did try to google for "start schema" concept definition and as far as I >see it is usually linked with OLAP not OLTP data models as here >(http://www.tdan.com/i021hy01.htm). >I did read first about star schema data models abstraction in a short >article in one of programming magazines somewhere in the summer 1995 and >since then I use this concept and it always work well am I building >datamodels from scratch or am I trying to understand/arrange existing >ones... > >Just wanted to share how (sometimes boring task) of getting well >understanding of an intersected net of an existing data model relationships >can be converted in a joyful(?) game of shuffling these table's >relationships to get at a clear view of the subject business area... > >Shamil > > > -- Marty Connelly Victoria, B.C. Canada