Robin Le Couteur NMIT Blog - 2018

Tuesday, April 10, 2018 NaLER Analysis In this class we looked at how to do a NaLER Analysis Here's some of the rules I picked up Step 1 - Determine the format of the model and make sure the model is consistently in that format Step 3 (For each entity) - 3.1 Construct a sentence for the primary key attribute/s of each entity: "Each <entity name> is uniquely identified by <primary key>" Make sure the primary key actually makes sense as the PK of the entity in question 3.2 One <E-name> identified by <PK> must have one <attribute name> 3.3 One <E-name> identified by <PK> <optionality><relationship-name><cardinality><E-name2> identified by <foreign key> One Zoo(Zoo_no) may house one or more Animal (Zoo_no, Animal_no) Step 4 (Populate the sentences from 3.2, 3.3 with these examples) - Zoo111 houses animal 'regents park 123' Zoo111 has the name 'reg...

Friday, April 6, 2018 Normalization Explained Update - Warning, this post has a number of errors lol. The BCNF example is not entirely correct, but it conveys some useful concepts to think about ;) I have written this blog as a way to concrete normalization concepts into my own mind, as well as to help as many other people as I can to understand normalization themselves. The information is not guaranteed to be correct, but I have done my best to make each form of normalization as simple as possible to understand using visualizations and examples. Before I start, it’s important to understand some concepts. Cardinality I find thinking about attributes as having cardinality within the table. In a Person table, PersonID has a 1 to 1 relationship with DoB. Think of it like the person only has one DoB, and the DoB is of that one person. For a multivalued attribute, it’s like one to many. One person can have many phone numbers, and each phone number only belongs to one...

Friday, April 6, 2018 Normalization This class we looked at normalization. Todd talked a bit about different forms and things like functional dependency, then we watched a 10min video about normalization to 5th normal form. It was useful cause I finally understand BCNF and the other higher forms of normalization. After that we got onto finishing milestone 2 of the practice assessment.