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Data are raw, unsummarized, unanylyzed facts or figures.
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Database (DB) is an organized collection of interrelated data.
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Database Management System (DBMS) — software that manages and controls access to the DB, providing a systematic way to create, retrieve, update, and manage data within the DB (e.g some type of [[SQL]]).
- The advantages of using a DBMS, rather than writing programs to access DBs directly, include:
- Data independence — applications are not exposed to data representation or storage details.
- Efficient data access — does not rely on good programmers.
- Data integrity and security — enforces integrity constraints.
- Data administration — single point of administration.
- Concurrent access
- Crash recovery
- Reduced application development time
- The advantages of using a DBMS, rather than writing programs to access DBs directly, include:
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There are different types of DBs:
- Flat file stores data in a single plain text file (e.g. CSV or Excel sheet). However, file based systems (systems with many flat files) have many disadvantages:
- Data integrity — no protection against invalid entries.
- Data redundancy and inconsistency — duplication of information.
- Data isolation — different locations.
- Atomicity — two users cannot update the DB at once and failure leaves files in an inconsistent state.
- Security — needs bespoke security in each application.
- Relational DBs — a shared collection of logically related data and its descriptions. It contains entities (e.g. people, places, things) and relationships (associations between the entities).
- Flat file stores data in a single plain text file (e.g. CSV or Excel sheet). However, file based systems (systems with many flat files) have many disadvantages: