Chapter 5 Flashcards
Database
A persistent organised store of data.
Persistent Storage
Non-volatile storage on a secondary storage medium such as a hard disk.
Data Duplication/Data Redundancy
Where the same data is stored more than once, unnecessarily.
Data Inconsistency
Where different versions of the same data have different values because duplicateversions have been stored and updated differently.
Program-Data Independence
Where the applications that use a shared database are separated from the actual data by a database management system. Changes can be made to one application without it affecting another.
DBMS
Stands for Database Management System, the system that separates theapplications from the data and provides features that allow database systems to becreated, interrogated and maintained.
Views
A feature of a DBMS that provides each application or user with specific accessrights and views of the database.
Flat File Database
A persistent organised store of data where data is stored in a single file organised into fields and records.
Relational Database
A persistent organised store of data where data is stored as a collection of related tables to minimise data redundancy.
Entity
A category of, for example, person (e.g. student, customer), object (e.g. classroom, stock item) or event (e.g. holiday booking, TV program) about which data is stored in a database, and which corresponds to a table in the relational database.
Table
A collection of data organised into records and fi elds within a relational database. A table represents a real world entity.
Record
Data stored about one instance of an entity: for example, one particular person or object
Field
One specific data item being stored such as surname or date.
Primary Key
A field in a table that uniquely identifies a record.
Foreign Key
A field in one table that is the primary key in another table and is used to create a relationship between those two tables.
Relationship
The logical connection created between two tables using a primary and foreignkey pair. It allows related data about a record to be accessed from another table. A relationship between two tables can be one-to-one, one-to-many or many-tomany.
Form
Input. An interactive window used for data entry that usually includes validationroutines, and uses controls such as combo boxes and radio buttons. Data input is usually saved to a database.
Validation
A check made by the computer to make sure the data is sensible.
Verification
A check to ensure that data has been input correctly. Sometimes this is done byprompting the user to read the data they have input and confirm it is correct. Other times the data has to be entered twice and one version is compared againstthe other to make sure it is the same.
Query
A feature of a DBMS that allows the database to be interrogated. It selectsrecords from the database based on specifi ed criteria.
Database Report
Output. A snapshot in time of the data from a database that can be printed. Data is formatted on a page and may be sorted or grouped. It may include totals.
Database Module
Section of code within a DBMS that allows the user interface to be tailored.
