INLS261 Tools for Information Literacy

Relational Databases

a database is a collection of related data
a database management system (or DBMS) is a system designed for two main purposes
1. to add, delete, and update data in the database
2. to provide various ways to view (on screen or in print) the data in the database
a flat file database is one where all the data is contained in a single table, such as in Excel
a relational database is one in which you can store information in different tables, each containing different information that relates to information in the other tables

to eliminate unnecessary redundancy or repetition in storage and in steps required for database maintenance
to be able to distribute the database to multiple locations, each with a responsibility to maintain a part of the total database

multiple tables, perhaps maintained by multiple locations
with relationships defined between the tables, so that the entire distributed, relational database works together

an entity (like the textbook for INLS261) is a concrete example of that description; in Access, it is a record
an entity class is composed of attributes; in Access, they are fields
- they include information we want in the database
- help to uniquely identify individual entities within a class
- can describe relationships between entities in different classes
an entity set (in Access, the table) is the list of given entities/records within a given entity class that are currently in the database/table

a Primary Key is a set of attributes/fields that uniquely identifies an entity/a record
a Foreign Key is a copy of the Primary Key of one entity class that appears as an attribute/field in another entity class and helps define the relationship between entities/records in the two classes
these keys link together the related tables in a relational database