Computer Science · Ch 8 — Database Concepts

Summary

A file in a file system is a container to store data in a computer.
A file system suffers from Data Redundancy, Data Inconsistency, Data Isolation, Data Dependence, and Controlled Data Sharing.
A Database Management System (DBMS) is a software to create and manage databases. A database is a collection of tables.
A database schema is the design of a database.
A database constraint is a restriction on the type of data that can be inserted into the table.
Database schema and database constraints are stored in the database catalog.
The snapshot of the database at any given time is the database instance.
A query is a request to a database for information retrieval and data manipulation (insertion, deletion, or update). It is written in Structured Query Language (SQL).
A Relational DBMS (RDBMS) is used to store data in related tables. Rows and columns of a table are called tuples and attributes respectively. A table is referred to as a relation.
Restrictions on data stored in an RDBMS are applied through the use of keys such as Candidate Key, Primary Key, Composite Primary Key, and Foreign Key.
A primary key in a relation is used for unique identification of tuples.
A foreign key is used to relate two tables or relations.
Each column in a table represents a feature (attribute) of a record. A table stores the information for an entity, whereas a row represents a record. …