Database Systems Chapter 6 Slides: Normalization of Database Tables

Normalization
Process for evaluating and correcting table structures to minimize data redundancies and anomalies.
Denormalization
Produces a lower normal form. Could lead to increased performance but greater data redundancy.
One
The Normalization Process— Each table should represent ????? subject.
Primary Key
The Normalization Process—
All non prime attributes in a table are dependent on the whole ??????
Anomalies
The Normalization Process— Each table is void of insertion, update, deletion ???????
Controlled Redundancy
The Normalization Process—
No data item will be unnecessarily stored in more than one table.
True
Objective of Normalization is to ensure that all tables are in at least 3NF True/False
Partial
Dependency– The determinant in a this dependence is only part of the primary key.
Transitive
Dependency– Exists when there is a functional dependence among nonprime attributes. (eg Y-> Z) (nonprime= not part of any candidate key)
Repeating Group
Group of multiple entries of the same type that exist for a single key attribute occurrence.
1NF
Eliminate the nulls and repeating groups. Identify the PK. Identify all dependencies.
2NF
Eliminate partial dependencies. Determine attributes with partial dependency and make new tables.
3NF
Eliminate transitive dependencies. Reassign corresponding dependent attributes.
Atomic
When an attribute cannot be subdivided.
Granularity
Level of detail represented by values (atomic data is at the lowest level.
Surrogate key
What kind of key can be used when the Primary Key is deemed unsuitable.
BCNF
Requires every determinany in table to be a candidate key. Only violated when table contains more than once candidate key.(when a nonprime attribute depends on another nonprime)
4NF
When one key determines multiple values of two other attributes that are independent of one another. Largely useless.
DO IT!
Look over the data modeling checklist. **SLIDE58**