Week 8 Flashcards
(21 cards)
What is a database?
A structured system that centrally coordinates related files (tables) to store and manage data efficiently.
Define logical view vs. physical view of a database.
Logical: User-focused view of how data is related (e.g., customer names and invoices).
Physical: Technical details of how data is stored (e.g., on a hard drive).
What are the components of a database table?
File/Table: Group of related records.
Record/Row: Group of related fields.
Attribute/Column: Specific characteristic (e.g., “Customer Name”).
Field/Cell: Intersection of a row and column.
Why use databases over legacy file systems?
Integration: Data linked across tables.
Minimized redundancy: No duplicate data (e.g., customer address stored once).
Consistency: Updates propagate automatically.
Give an example of data inconsistency in legacy systems.
A customer’s address might be “CJ Jackson” in the sales file and “Charles Jackson” in the customer file.
What is a primary key of a relational database?
A unique identifier for a row in a table (e.g., Sales Invoice #).
What is a foreign key a relational database?
A field linking two tables (e.g., Customer # in the Sales table references the Customer table).
What are the three anomalies in poorly designed databases?
Update anomaly: Inconsistent data after partial updates.
Insert anomaly: Cannot add records without redundant data.
Delete anomaly: Loss of critical data when deleting a record.
What is normalization?
Organizing data into related tables to minimize redundancy and anomalies.
What is referential integrity?
Foreign keys must match existing primary keys in related tables.
What is a query?
A request to retrieve specific data (e.g., “Show invoices for customer D. Ainge”).
What is the REA model?
A framework for accounting databases focusing on:
Resources (e.g., cash, inventory),
Events (e.g., sales, purchases),
Agents (e.g., customers, employees).
What is an ER diagram?
A visual tool showing relationships between entities (e.g., Customer ↔ Sale) and their cardinality.
Define cardinality in ER diagrams.
The degree of participation between entities:
1:1 (one department head per department),
1:N (one customer → many sales),
M:N (students ↔ courses).
What is a schema?
A technical plan describing the database structure (tables, relationships, data types).
What is a data dictionary?
A detailed blueprint of data elements, field types, and relationships.
What are the three DBMS languages?
DDL (Data Definition Language): Builds the database structure.
DML (Data Manipulation Language): Edits data (insert/update/delete).
DQL (Data Query Language): Retrieves data (e.g., SQL SELECT).
How are Sales, Customer, and Inventory tables linked?
Sales table uses Customer # (foreign key) to link to Customer table.
Sales-Inventory table links Item # to Inventory for pricing.
What is a bad database design example?
A student table with repeated address fields for every unit enrollment (causing redundancy).
Why are accountants involved in database design?
They ensure data accuracy, assess feasibility, and estimate ROI.
What are the steps in database design?
Data modeling (REA/ER diagrams).
Conceptual design (schema).
Implementation (coding with DBMS languages).
