Information Systems & Databases Flashcards
What does FROM do?
FROM - selects the table you which to extract data from
What does SELECT do?
SELECT - takes the data from the nominated table
What does WHERE do?
WHERE - allows the user to specify what they want to search for (the search criteria)
Describe what a Flat-File Databse is?
All of the data is recorded in one table or file. Suitable for small databases. Can only manage one database at a time.
Describe what a Relational Database is.
A set of tables in a database that are linked to each other. Allows you to manage and use several separate databases. Called relational because it’s a type of database that allows you build relationships between different tables and databases.
What is a Primary Key?
It is a field that is used to uniquely identify a record in a table or relational database. The data is not replicated anywhere else in the database and it cannot be a null value (blank).
What is a Foreign Key?
A primary key in one table, but a secondary key field in another table. It’s used to establish a relationship between two or more tables. They cannot exist in a flat file database and are only found in relational databases.
A Schema or Schematic Diagram is…..
an organised plan of the entire database that shows the tables, the fileds of the tables, and the relationships between them.
What is the difference between Entities and Attributes in a schema?
Entities are the Tables in a database.
Attributes are the Fields in the tables.
A type of relationship that occurs when each record in the first entity (table) is related to exactly one record in the second entity (table)
One-to-One Relationship
A type of relationship that occurs when one record in the first entity (table) is related to many records in the second entity (table), but any record in the second entity (table) only relates to one record in the first entity (table).
One-to-Many Relationship
A type of relationship that occurs when each record in the first entity (table) is related to many records in the second entity (table), and each record in the second entity (table) is related to many records in the first entity (table).
Many-to-Many Relationship
A type of access method used when accessing a storage medium such as magnetic tape.
Sequential Access
A type of access method used when accessing a storage medium such as magnetic disk, CD’s or flash drives
Direct Access
A database that is located, stored, and maintained in a single location.
Centralised Database
A database located at more than one site that acts as a single collection of data, but is geographically dispersed.
Distributed Database
There are 6 relational operators used in SQL.
What are they?
Equal to =
Not equal to <>
Less than <
Greater than >
Less than and equal to <=
Greater than and equal to >=
What is Data Mining?
It is the process of looking for trends in the data stored in databases. It discovers patterns that predict future behaviour based on past trends. Patterns may be coincidental or have no real world significance. This is able to occur as a result of the improvements in technology.
List the three generations of backup master files
Grandfather - Oldest backup
Father - Second Oldest backup
Son - Newest backup
List some disadvantages of paper records
Paper deteriorates over time
Bulky to store
Data cannot be altered or deleted easily
Data can only be sorted by one field
Describe Batch Transaction Processing
In a Batch Tranaction Process, transactions are accumulated over a period of time and processed as a single unit, or batch at a later time. Whatever the time period in a batch system, there is some time delay between the actual event and the processing of the transaction to update the records of the organization.
Eample 1 = A store may update its sales records every day after the store closes.
Example 2 = A payroll system may process all the time cards every two weeks to determine employee earnings and produce paychecks.
Describe Real Time Processing
In a real-time processing system, transactions are processed immediately as they occur without any delay to accumulate transactions. Real-time processing is also referred to as online transaction processing, or OLTP. In this case, the records in the system always reflect the current status.
Example 1 = A good example of a real-time processing system would be airline ticket reservations. When you book a ticket and select a seat, that booking is made right away, and nobody else can get that same seat even a second later. Any changes you make to your reservation are also updated in real time.
Example 2 = The stock market. When you submit an order to buy a stock, that order is processed immediately and not at the end of the day.
Describe what a Decision Support System does
A Decision Support System takes data from a Transaction Processing System (TPS), a Management Information System (MIS) and data from other external sources to help make decisions.
Name 5 different information technologies
Networked Computers
Keyboards
Monitors
EFTPOS machines
Barcode Scanners
LAN / WAN
Printers
Photocopiers
Camera
Variety of software applications
Name 5 different office automation systems
Word Processors
Database Management System software (DBMS)
Voice Mail / E-mail
Scheduling Software (MS Project)
Spreadsheets
Desktop Publishing software (DTP)
What are some advantages of computer- based information systems over manual systems?
Considerably faster
Data does not have to be in a set order
Data management is much faster
Data can be exchanged easily between applications and over networks
Easily edited and can store large amounts of data.
What is a DBMS
Database Management system
