chapter 4 Flashcards
(17 cards)
Q: What is logical database design?
A: Logical database design is the process of organizing data into structured tables based on relationships, ensuring it is free of redundancy and inconsistencies.
Q: What is normalization?
A: A step-by-step process to organize data into tables to minimize redundancy, avoid anomalies, and maintain consistency.
Q: What are the main goals of normalization?
Reduce redundancy.
Avoid anomalies in data insertion, deletion, and updates.
Improve data integrity.
Q: What are the three types of functional dependencies?
Full Dependency: A non-key attribute depends on the entire primary key.
Partial Dependency: A non-key attribute depends on part of a composite key.
Transitive Dependency: A non-key attribute depends indirectly on a key.
Q: What is the condition for a table to be in First Normal Form (1NF)?
All attributes must be atomic (indivisible).
No repeating groups or arrays are allowed
Q: How do you move from 1NF to 2NF?
Eliminate partial dependencies by splitting tables.
Ensure non-key attributes depend on the whole primary key.
Q: What is the condition for a table to be in Second Normal Form (2NF)?
Must be in 1NF.
No partial dependencies are allowed.
What is the condition for a table to be in Third Normal Form (3NF)?
A:
Must be in 2NF.
No transitive dependencies are allowed.
: What is a functional dependency, and can you give an example
A relationship where one attribute uniquely determines another.
Example: StudentID → StudentName (StudentID determines the StudentName).
Q: What is a transitive dependency, and can you give an example?
When a non-key attribute depends on another non-key attribute indirectly through a key.
Example: StudentID → AdvisorID and AdvisorID → AdvisorName implies StudentID → AdvisorName.
Q: What are the three normal forms in logical database design?
1NF: Eliminate repeating groups and make data atomic.
2NF: Eliminate partial dependencies.
3NF: Eliminate transitive dependencies.
Q: What is an update anomaly?
A: An inconsistency caused when updating data in one place but not in others.
Q: What is a deletion anomaly?
A: Loss of valuable information when a row is deleted.
Example: Deleting a course record might delete the professor’s data too.
Q: What is an insertion anomaly?
A: Difficulty inserting data due to missing required information.
Example: Unable to add a student without assigning them a course.
Q: Why is normalization important?
A: To reduce redundancy, ensure data consistency, and make databases easier to maintain and update.
