Untitled Deck Flashcards
What is a Many-to-Many relationship?
A relationship where many records in one entity are associated with many records in another entity.
What is a Many-to-One relationship?
A relationship where many records in one entity are associated with one record in another entity.
What is a One-to-One relationship?
A relationship where one record in an entity is associated with only one record in another entity.
What is a Star Schema?
A data-modeling technique that organizes data into fact and dimension tables, often used in data warehouses.
What does a Fact Table contain?
Contains numeric data (e.g., sales, revenue).
What do Dimension Tables contain?
Contain descriptive attributes (e.g., time, geography).
What is the relationship between Fact and Dimension Tables?
The fact table is connected to dimension tables in a many-to-one (M:1) relationship.
What are the stages of the Systems Development Life Cycle (SDLC)?
Planning, Analysis, Detailed Design, Implementation, Maintenance.
What is the first stage of the SDLC?
Planning: Determine the project’s scope and objectives.
What is the purpose of the Analysis stage in SDLC?
Define system requirements and identify challenges.
What is involved in the Detailed Design stage of SDLC?
Outline system specifications.
What happens during the Implementation stage of SDLC?
Code and deploy the system.
What is the final stage of SDLC?
Maintenance: Regular updates and bug fixes.
What are the stages of the Database Life Cycle (DBLC)?
Initial Study, Database Design, Implementation and Loading, Testing and Evaluation, Operation, Maintenance and Evolution.
What is the first stage of the DBLC?
Initial Study: Analyze requirements and constraints.
What occurs during the Database Design stage of DBLC?
Develop logical and physical models.
What happens in the Implementation and Loading stage of DBLC?
Create database structures and load data.
What is the purpose of the Testing and Evaluation stage in DBLC?
Verify functionality and performance.
What occurs during the Operation stage of DBLC?
Begin database use and monitor.
What is the final stage of DBLC?
Maintenance and Evolution: Regular updates and adjustments.
What is Data Mining?
The process of analyzing large datasets to discover patterns and extract meaningful information.
What is Predictive Analytics?
Uses data mining, statistics, and machine learning to predict future outcomes.
What is a Data Warehouse?
A central repository for integrated, subject-oriented, time-variant, and nonvolatile data supporting decision-making.
What is a Data Mart?
A smaller, focused subset of a data warehouse for specific business units.
What does ETL stand for?
Extract, Transform, Load.
What is the Extract phase in ETL?
Retrieve data from various sources.
What is the Transform phase in ETL?
Clean and format data.
What is the Load phase in ETL?
Store data in a target database.
What are ETL Tools?
Software that automates the ETL process (e.g., Informatica, Talend).
What are the 3 V’s of Big Data?
Volume, Velocity, Variety.
What is a Primary Key?
Uniquely identifies a row in a table.
What is a Foreign Key?
A primary key from another table, establishing a relationship.
What is a Candidate Key?
Any attribute or combination of attributes that can serve as a primary key.
What is the syntax for an Insert Statement in SQL?
INSERT INTO table_name (columns) VALUES (values).
What is the syntax for a Delete Statement in SQL?
DELETE FROM table_name WHERE condition.
What does Truncate do in SQL?
Deletes all rows but keeps the table structure.
What does Drop do in SQL?
Deletes the entire table structure.
What are Aggregate Functions in SQL?
Functions like SUM(column) and COUNT(column) that perform calculations on data.
What does GROUP BY do in SQL?
Groups rows that have the same values in specified columns.
What is an Inner Join?
Returns rows with matching values in both tables.
What is a Left Join?
All rows from the left table and matching rows from the right.
What is a Right Join?
All rows from the right table and matching rows from the left.
What is an Outer Join?
Includes matched and unmatched rows from both tables.
What is a Surrogate Key?
A system-generated unique key with no intrinsic business meaning.
What are NOT NULL constraints?
Disallows null values.
What are UNIQUE constraints?
Ensures all values in a column are unique.
What are CHECK constraints?
Validates attribute values.
What are Optional Relationships in ERD?
A relationship where an entity instance can exist without being related to another entity.
What are Mandatory Relationships in ERD?
An entity instance must have a corresponding instance in a related entity.
What is DDL?
Data Definition Language: Commands like CREATE, ALTER, DROP.
What is DML?
Data Manipulation Language: Commands like INSERT, UPDATE, DELETE.
What does UNION ALL do?
Combines datasets and retains duplicates.
What does UNION do?
Combines datasets and removes duplicates.
What does INTERSECT do?
Returns only common rows.
What does EXCEPT do?
Returns rows in the first dataset but not in the second.
What is a Supertype?
A general entity type.
What is a Subtype?
A specialized entity inheriting from the supertype.
What does Hierarchy support in terms of entities?
Supports attribute inheritance.
