DEFINITION OF DATA MODEL
Is the process of structuring and organizing data.
TYPES OF DATA MODELS
(1) Flat (2) Hierarchical (3) Network (4) Relational (5) Object-Relational and (6)Star Schema
SIGNIFICANCE OF DATA MODEL
(1) A well-developed data model can foster improved understanding of the organization
(2) Data model helps in structuring and organizing of data
(3) It imposes constraints or limitations on the data placed within the structure
STANDARD DATA MODEL
A standard data model or industry standard data model is a data model that is widely applied in some industry and shared amongst competitors to some degree. Examples are: ISO 10303, ISO 15926, IDEAS GROUP
NORMALIZATION
Is the process of efficiently organizing data in a database by reducing duplication or redundancy and design flaws.
NORMAL FORM
Provide criteria for determining a table’s degree of vulnerability to logical inconsistencies and anomalies.
CLASSES OF NORMAL FORM
1st, 2nd, 3rd, BNC, 4th and 5th normal forms
DETERMINANT OF NORMAL FORM
(1) The minimal number of attributes necessary to support the data requirements of the enterprise
(2) Attributes with a close logical relationship are found in the same relation
(3) Minimal redundancy with each attribute represented only once with the important exception of attributes that form all or part of foreign keys.
EVALUATION
- Define data model
- State types of data model
CONCEPT OF KEYS
PRIMARY KEY
Is the attribute used to identify a record uniquely in a table or database
COMPOSITE PRIMARY KEY
Two or more keys used as a primary key
FOREIGN KEY
Is the field or attribute of a table that matches the primary key of another table.
ENTITY RELATIONSHIP DIAGRAM (ERD)
Is the diagram that illustrates the logical structure of a database.
Components of Entity-Relationship (1) Entities (2) Attributes (3) Relationships
ENTITY
Is anything for which data can be written about in a business.
ATTRIBUTES
Are data elements that have the smallest units of data that can be described in a meaningful manner.
RELATIONSHIP
Is an association among the instances of one or more entity types
CARDINALITY
Defines the relationships between the entities in terms of numbers.
TYPES OF RELATIONSHIP
One-to-One, One-to-Many, Many-to-Many
GENERAL EVALUATION
- (a) Define data model?
(b) State types of data model
(c) Use the following data to draw a hierarchical data model: Fruit; Orange, Pear, Berry; Lime, Grape,Avocado, Sour Sop, Raspberry, Cranberry [Hints: Lime and Grape are children of Orange, Avocado, and SoarSopare children of Pear while Raspberry and Cranberry are children of Berry]
- (a) State five (5) classes of normal forms
(b) Bring the table below to Second Normal Form
TABLE_PURCHASE
| CustomerID | StoreID | Purchase Location |
| 1 | 1 | Lagos |
| 1 | 3 | Kano |
| 2 | 1 | Lagos |
| 3 | 2 | Abuja |
| 4 | 3 | Kano |
Hint: This table has a composite primary key [CustomerID, StoreID]
WEEKEND ASSIGNMENT
- Data models describe ……… data for storage in data management systems (a) structured (b) unstructured (c) integer (d) alphabetic
- Which of this is not an example of standard data model (a) ISO 10303 (b) ISO 15926 (c) IDEAS GROUP d) Good shepherd
- ……….. key is a field in a relational table that matches a primary key of another table (a) foreign (b) surrogate (c) primary (d) candidate
- ……………. is graphical representation of entities and their relationships to each other (a) Entity-Relationship Diagram (b) Entity-Relationship Picture (c) Entity-Relationship Data (d) Entity-Relationship Symbol
- A roof covers a building describes …………relationship (a) one-to-one (b) one-to-many (c) many-to-many(d) none of the above
THEORY
- (a) Define the following terms (i) Entity (ii) Attribute (iii) Relationship
(b) What is cardinality?
(c) Mention and explain three types of relationship in ERD with one example each
- (a) Define the following (i) Primary key (ii) Foreign key (iii) Composite primary key
(b) Explain the term Normal Form.
(c) Design a database of your choice indicating the primary key and the foreign key
See also