WEEK THREE
TOPIC: DATA MODELS II
TYPES OF DATA MODELLING
Flat Model: The flat Model (or Table) model consists of a single, two-dimensional array
of data elements, where all members of a given column are assumed to be similar in
values, and all member of row are assumed to be related to one another.
Flat Model
Route No. Miles Activities
RECORD 1 1 – 95 12 Overlay
RECORD 2 1 -495 05 Parching
RECORD 3 SR – 301 33 Crack Seal
HIERARCHICAL MODEL
In a hierarchical database, data is organized into an upside-down tree-like structure,
implying a single upward link in each record to describe the nesting, and a sort field to
keep the records in a particular order in each same-level list. Hierarchical structures
were widely used in the early mainframe database management systems.
Hierarchical Model
Network Model: This model organizes data using two fundamental construct, called
records and sets. Records contain fields, and sets define one-to-many relationships
between records: one owner, many members.
EVALUATION
1. Differentiate between Hierarchical and Network Model.
2. Explain Flat data model.
Relational Model
The relational model or relational data base model is based on first-order predicate
logic. Its core idea is to describe a database as a collection of predicates over a finite
set of predicate variables, describing constraints on the possible values and
combinations of values.
Object-Relational Model
The object relational model is similar to relational database model, but objects, classes
and inheritance are directly supported in database schemas and in the query language.
An object-relational database can be said to provide a middle ground between relational
databases and object-oriented databases (OODBMS)
Star Schema
The star schema is the simplest style of data warehouse schema. The star schema
consists of a few “fact table” (possibly only one, justifying the name) referencing any
number of dimension tables”. The star schema is considered an important special case of
the snowflake schema.
SIGNIFICANCE OF DATA MODELS
1. Data model is detailed enough to be used by the technical team
for building the physical database.
2. The information contained in the data model will be used to
define, relational tables, primary and foreign keys, stored
procedures, and triggers.
3. Data model make sure that all data objects provided by the
functional team are completely and accurately represented.
4. Data model gives a specific model or structure to a database.
5. Data model defines the set of operations that can be performed in
a database.
6. Data model help to determine the structure that will avoid
redundancy of data.
WEEKEND ASSIGNMENT
Instruction: Choose the correct option from the ones lettered A to D
1. One of the following is an example of a DBMS package.
(a) Ms Word (b) Ms Power-point (c) Ms access (d) Ms Outlook
2. In the approach of data modeling ____ data modeling identifies the highest
level relationship between different entities.
(a) Conceptual Data Modeling
(b) Logical Data Modeling
(c) Flat data Modeling
(d) Physical Data Modeling
1. ____ model organizes data using two fundamental construct called record and
set.
(a) Network (b) Relational (c) Object Oriented (d) Star Schema
2. ____model consists of a single, two-dimensional array of data elements.
(a) Network (b) Relational (c) Object Oriented (d) Star Schema
3. ____database model is organized into an upside-down tree-like structure
(a) Network (b) Relational (c) Object Oriented (d) Hierarchical
SECTION B
1. List and explain four types of database model
2. Define the following; Data, Field, record, File.
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