WikiGalaxy
Entity-Relationship Design Issues
Redundancy
Redundancy in ER design refers to the unnecessary duplication of data, which can lead to inconsistencies and increased storage costs. It often occurs when the same piece of information is stored in multiple places.
Incomplete Relationships
An incomplete relationship in an ER model can lead to an inability to capture certain data dependencies or interactions between entities, resulting in incomplete data representation.
Entity Splitting
Entity splitting involves dividing a single entity into multiple entities, which can complicate the design and make it difficult to maintain data integrity across related entities.
Improper Use of Attributes
Attributes should be used properly to ensure that all necessary data is captured. Misuse or overuse of attributes can lead to confusion and complexity in the database design.
Weak Entity Identification
Weak entities rely on other entities for their identification. Failing to properly identify weak entities can result in loss of data relationships and integrity.
-- Example of Redundancy
CREATE TABLE Employees (
EmployeeID INT PRIMARY KEY,
Name VARCHAR(100),
DepartmentID INT,
DepartmentName VARCHAR(100) -- Redundant data
);
Normalization
Normalization is a process used to reduce redundancy and improve data integrity by organizing fields and table relationships in a database.
Use of Foreign Keys
Foreign keys are crucial for maintaining relationships between tables and ensuring referential integrity in a database.
Data Integrity Constraints
Data integrity constraints ensure that the data entered into a database remains accurate and consistent over time.
Entity Generalization
Entity generalization is a process of defining a generalized entity from multiple specialized entities, which can simplify the ER model.
Proper Use of Primary Keys
Primary keys uniquely identify each record in a table and are essential for ensuring that each entity instance is distinct.
Console Output:
Query executed successfully.
