Hi, all!
I just got our class capture link from FOX IT this afternoon. You can also find the link on our community website under LINKS in the sidebar.
The due of ICA 2 has been extended to this Thursday! We will do the ICA on our Thursday class! If you cannot wait to play with ERDPlus until our next class, try to get familiar with the platform and all the ER modeling we have covered so far, and then feel free to draw your very first ERD.
Remember to label the cardinality between entity A and entity B following the three steps:
- Read from entity A to the other entity B;
- First, consider the minimum cardinality of the A-to-B relationship and mark an “optional” relationship as “0”, or a “mandatory” one as “|” on the line connected to entity B;
- Then discuss the maximum cardinality of the A-to-B relationship and mark “one” as “|”, or “many” as “⚟” next to the minimum cardinality in step 2;
- Repeat 1 through 3 for B-to-A relationship.
TIPS:
- ONE relationship(diamond) can ONLY link TWO entities(rectangles). If one needs more connections, it should be a NEW entity! (E.g., transaction, order, record, etc.);
- Relationship attributes only exist for many-to-many relationship(Why? It is unnecessary to add a relationship attribute for a one-to-one/one-to-many relationship, we can simply add it as an entity attribute for the entity on the one side.) ;
- If a noun has no attribute in the requirement statement gathered from the user side, we do NOT model it as an entity.
Enjoy your night and look forward to seeing you all on Thursday!
Best,
Zhe (Joe) Deng
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