Information System and Databases Flashcards
What are some computer-based methods of organising?
– flat-file systems
– database management systems
– hypermedia
What are the advantages of computer-based methods of organisation compared to non.
- Easily edited
- Large storage
- Fast retrieval
- Display options
What is the hierarchy of flat-file structures.
File < Record = Field < Character
Describe the keys in a flat-file structure.
A single key is a field in which each item of data is unique.
A composite key, or compound key, is made by joining two or more fields
together.
A primary key is a single key or compound key that must have a value.
A secondary key is a field that contains useful items of data often used in
searches.
What do schemas consist of?
- Entities
- Attributes
- Relationships
What are data dictionaries?
Comprehensive description of each field, organised in a table format.
- Field Name
- Data Type
- Field Size
- Description
- Example
Describe the similarities and differences between flat-file and relational databases.
- FF is one table, RD is multiple.
- RD enforces data integrity, FF no
- RD use relational data model, FF use flat data model
- RD uses SQL, FF uses simple file operations
- RD optimised for performance, FF can be slow
- RD used to large amounts of data, FF no
-Both store, organise, retrieve and backup data.
What are tags in HTML?
<html>
<head>
<TITLE> HTML </TITLE>
</head>
<body>
<h1>HTML document </h1>
<p>Welcome. This is a paragraph in HTML.
It is just text!</p>
<p>This is another paragraph in HTML.
HTML is easy.</p>
</body>
</html>
What are standard SQL commands?
SELECT
FROM
WHERE
ORDER BY
Describe the principles of the operation of a search engine.
A database of indexed Web sites that allows a keyword search. Involves spiders following hyperlinks and acquiring URLs.
What are some backup and security methods?
Encryption
Firewall
