Comp 1: Intro to Databases Flashcards
What is data?
Numbers, text, visual, or audio info that describes real-world systems.
What are three ways data varies?
- Scope, 2. Format, 3. Access
What is a database?
Collection of data in structured format.
What is a database system also known as?
Database Management System (DBMS)
What does a DBMS do?
software which reads and writes data in database. Ensures security, consistency, and availability.
What is a query language?
Specialized programming language for designed for db systems.
What is Database Application?
Programmers write the query languages into friendly GUI.
What are the 4 Database Jobs?
- DB Administrator. Secures DB system.
- DB Designer. Determines format and structure. Storage, response time, and support.
- DB Programmer. Writes the apps which combine query and general programming languages.
- DB User. The person who uses it.
5 requirements for a database use by many users.
- Performance
- Authorization
- Security
- Rules
- Recovery
What is a transaction?
Group of queries that must be completed or rejected as a whole. (p^q)
What 3 things does a DB do when processing transactions?
- Ensure p^q. Complete entire transaction or not at all.
- Prevent conflicts between concurrent transactions.
- Ensure results are never lost.
What is the architecture of the database system?
Internal components and relationship between those components.
What are the 5 components of a DB system and what do they do?
- Query Processor. Interprets and returns results of query.
- Storage Manager. Translates query processor to low-level file system commands.
- Transaction Manager. Makes sure transactions are done appropriately. Restores back up if system fails.
- Log. Contains records of everything.
- Catalog. Directory of tables, columns, indexes etc.
What is big data?
Gigantic clusterfuck of data uploaded to the internet in the 90s and early 2000s.
What are non-relational systems called?
NoSQL
Are most DB systems Open Source or Proprietary?
Open Source
What are the top 5 DB products today?
- Oracle (proprietary)
- MySQL (open source)
- SQL Server (proprietary)
- PostgreSQL (open source)
- MongoDB (open source)
How was SQL originally developed?
IBM in the 1970s as prototype for relational databases.
What is a query?
Command which inserts, retrieves, updates, or deletes data. CRUD (create, read, update, delete)
What are 4 common SQL commands?
INSERT, SELECT, UPDATE, DELETE
What are the main 4 data types used in CREATE TABLE?
INT
DECIMAL
VARCHAR
DATE
What is the analysis phase?
Specifies reqs for DB. Entities, relationships, attributes, etc.
What do ER diagrams represent?
Entities, relationships, and attributes.
What are the symbols used in ER Diagrams for each represented concept?
- Rectangles = entities
- Lines between = relationships
- Text inside = attributes
What is logical design?
Plans the DB. Shows how logic will flow from one piece to another. Also called Schema.
What are keys?
Column used to ID individual rows of a table.
