Databases Flashcards
What is a database?
a persistent store of organised data which allows data to be queried/interrogated.
What does persistent store mean?
Once data is put into the database it is stored in non-volatile storage and can be accessed again later
Give some examples of places which have databases
School, Doctors, Dentists, Online Shopping, Social Media
What does DBMS stand for?
DataBase Management System
Why is the DBMS desirable?
- its a standard way of accessing data
- it gives security
- it can have multi user access
- there is data maintenance
What is a flat file database?
a database that only has one table
What is a relational database?
a database with more than one table
What is data redundancy?
when data is duplicated
What are some features of the DBMS?
- A command language
- a data manipulation language
- a data dictionary
- provides security
- the ability to view from different viewpoints
What does each table/entitity have?
its own unique identifier (primary key)
What is a record?
A row on the table
What is a field?
a column of the table
What is a form?
An input screen allowing chosen data items to be displayed and edited
uses texboxes/drop down lists/checkboxes etc…
when edited, the changes are updated in the
database
What is a query?
used to search and filter in a database
What is a Report?
An output of the data in a database
a snapshot of the data at a given time/when printed of specified fields/Laid out in a specified format
What is a Module?
a pre-written program in database software
What does using the logic operator AND do in a query?
makes sure both criteria are met
What does using the logic operator OR do in a query?
makes sure one of both of the criteria are met
What language are queries written in?
SQL
What does the presence check do?
checks if data has been entered into the field
What does to range checks do?
ensures that numerical data is between a particular range
What does a length check do?
if the data is too short or too long it would not be valid
What does the format check do?
ensures the data is in a particular format
What does the lookup check do?
looks up the data and checks it exists
What does check digit do?
the computer performs a calculation to check the numbers are right
Why is data separated from applications?
gives the user a greater flexibility in how the data can be used.
Why is a foreign key needed?
to link tables, allows you to retrieve data from another a table and avoids you re-writing data everytime. avoids data redundancy
What is an entity?
A real world object which data is stored about in a database. They are the tables.
What different relationships between tables can there be?
one-to-many
many-to-many
one-to-one
What is the DBMS?
- Database Management System/Used to manage
the database - May use SQL/allows database to be queried
- Provides facilities for creating tables/inserting
data - Allows data structure to be independent of the
program - Allows relationships to be created between
tables - Provides security features/levels of access
What is HTML?
- HyperText Mark-up Language
- Text file containing the text to be displayed uses tags which indicate how to display it location of pictures/other elements to include and hyperlinks to other locations/URLS
Why is HTML used?
Because it is an open/accepted standard data will display correctly on all browsers which conform to the standard
