March 3, 2010 at 11:03 am
I am almost embarrassed to ask this question (almost). I have really tried to find the answer.
In an effort to learn more about SQL Server, I have been doing a lot of reading. The books that I have looked at describe the relationships between the tables. I completely understand those relationships. What I don't understand is how to figure out what the relationships are between the tables from looking at a database diagram.
The book that I am currently reading has an example of two tables:
Category and Product
Next to the Category table they have a diamond, followed by a dotted line and an arrow that points to the Product table.
Category <> --------> Products.
Logically I would assume that each Category has many products. If that's correct shouldn't the diamond be next to the Product table and the arrow next to the Category?
Can someone please explain a) the meaning of these symbols and b) explain the relevance of the placement of these symbols.
Thanks
March 3, 2010 at 1:40 pm
I think wikipedia can explain it better than I. Have a look at the following article, including the section on differences in notation...
http://en.wikipedia.org/wiki/Entity-relationship_model
-Luke.
March 3, 2010 at 5:16 pm
Luke L (3/3/2010)
I think wikipedia can explain it better than I. Have a look at the following article, including the section on differences in notation...http://en.wikipedia.org/wiki/Entity-relationship_model
-Luke.
Thank you so much. I felt foolish asking this question, but I couldn't seem to find the answer.
March 3, 2010 at 7:16 pm
No need to feel foolish. It was a good question. Having a solid understanding of ERD's and at least some familiarity (knowing where to look) when you come across a format you don't recognize is very important.
Never feel bad about asking for help, a large part of learning is figuring out what you don't know and not being afraid to go and find help.
-Luke.
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