1. Relational Model and ER Model: in a Nutshell
P. Pete Chong
11/14/2018

2. Relational Model A Model based on “relations”
A “relation” is a two-dimensional table
Each row is called a “tuple”
Each column is call an “attribute”
11/14/2018

3. Entity-Relationship Model
Entity is a “thing” – a collection (table) of attributes that are organized by relevance and usage.
Relationship is how data are used together
Three cardinalities: 1:1, 1:m, m:n
11/14/2018

4. Create “Well-Structured” Tables Using ER Model
Identify Entities and their Relationships and draw 1ERD
Convert 1ERD to 2ERD
1:1 – merge the tables
1:m – the primary key of 1 side becomes the foreign key on the m side
m:n – create a third table that uses primary keys on both sides as composite key
11/14/2018

5. Create “Well-Structured” Tables Using Normalization
1NF: no repeating groups
2NF: non-key attributes are functionally dependent on the primary key
3NF: no transitive dependency
DK/NF: every constraint on the relation is a logical consequence of the definition of keys and domain
11/14/2018

6. Result
All tables are in 3NF – which eliminates most of the anomalies already
Each table contains one theme
11/14/2018