Week 9 - it was hard!

With the ERD diagramming project this week I kept getting caught up in the differences between a one to many versus the zero to many relationship between entities (I am also praying there is a difference between these and a many to many relationship ). I thought I had a fair idea after my initial read through but when actually diagramming kept getting hopelessly confused. Every time I tried to begin again I worked out a different diagram. Eventually, and I know this sounds obvious but it really did take me some time, I realized I needed to define some relationships myself. Some of the relationships were pre-determined by their nature but several could be open to interpretation. Which is why it is called a planning process. I can see how other people would come to different conclusions and that these differences might make for significant differences in end-user results. My final ERD diagram tries to make my decisions clear and I either did it or I have mucked the whole thing up. Returning to the readings while I was working all this out actually did not help me much. The Mostafa tutorial on tables ultimately was the basis of my Eureka moment. I am curious if others found that there seemed less uniformity in the Crow's Feet notation than I was comfortable with. For example I couldn't tell if the flat or dotted line between entities (shown in the Perfect Fit article) was universally applied as I did not see it in other readings or examples I found on the web. I think experimenting with different types of information and uses, looking over examples and a great deal of experience are required to reach any competency in this field and has given me new respect for database designers.