Understanding databases Flashcards
General questions to test knowledge about databases (19 cards)
What is a database?
A structured data storage designed for ease of data accessibility, manipulation, and manageability.
Why use a database instead of storing data in files?
Databases support data integrity, allow constraints, enable efficient querying, and provide better security through authentication and authorization.
What is structured data?
Data that can be organized in tables, such as relational databases, spreadsheets, or logs.
Give 3 real-world examples of structured data.
Relational database with customer records, Excel employee spreadsheet, bank transaction log.
What is unstructured data?
Data that lacks a predefined format, and cannot be organized in tables.
Give 3 real-world examples of unstructured data.
Social media posts, scanned PDF contracts, audio files from support calls.
What are ACID properties in databases?
Atomicity, Consistency, Isolation, Durability — they ensure reliable transactions.
What does Atomicity ensure?
That a transaction fully succeeds or fully aborts — no partial changes.
What does Consistency ensure?
That the data remains valid before and after a transaction.
What does Isolation ensure?
That transactions do not interfere with each other.
What does Durability ensure?
That once committed, a transaction’s changes are permanently saved.
Why are queries better than file system searches?
Because queries allow targeted retrieval, while file systems often require full scans.
Why are constraints important in databases?
They enforce data correctness, preventing invalid or absurd entries.
How do databases offer better security than files?
Through authentication and authorization mechanisms.
List four main types of databases.
Relational, NoSQL, Graph, Object-Oriented.
Which type of database uses tables and keys?
Relational databases.
Which type of database is best for unstructured or flexible data?
NoSQL databases.
Which database type focuses on relationships and connections?
Graph databases.
Which database stores data like object-oriented code?
Object-Oriented databases.
