Chapter 5- DATABASES Flashcards
What is meant by a range check
A range check validates data that falls between two extreme values
Explain the term verification
Verification is a check that data is correct, compared with the source or duplicate file
What is a check digit
An extra digit added to a data item produced by an algorithm or calculations
Surname
Length, type
Date of birth
Length, range
Gender
Length, type
Credit limit
Number, range
Telephone number
Length, type
Password
Length, type
Define the term data redundancy
The unnecessary repetition of data
Explain how data redundancy affects this table
City names are repeated
Explain what problems could occur due to data redundancy
Alternative spellings might be used so data is not found
Explain how the data could be stored to eliminate this problem
Store city names and addresses in separate tables
Explain what DBMS is
Database management software that controls the setting up and interrogation of a database
What is a database
A store of persistent and organised data
What is a flat file database
A flat file database consists of only one table
What is a relational database
Data stored in tables, linked in key fields with each row the same structure and size
Describe four features of a typical DBMS
Forms
Reports
Queries
Tables
Describe the difference between an entity and a table
An entity is a real world object, a table is a data structure that holds data about an entity
Describe two ways in which a query can be constructed
QBE, a visual interface or programmed query language
Define the term validation
Validation is a check on data as it is input carried out by a software or the computer
