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27 Cards in this Set
- Front
- Back
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What does FROM do?
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FROM - selects the table you which to extract data from
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What does SELECT do?
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SELECT - takes the data from the nominated table
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What does WHERE do?
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WHERE - allows the user to specify what they want to search for (the search criteria)
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Describe what a Flat-file Databse is?
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All of the data is recorded in one table or file. Suitable for small databases.
Can only manage one database at a time |
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Describe what a Relational Database is.
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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.
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What is a Primary Key?
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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).
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What is a Foreign Key?
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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 only found in relational databases.
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A Schema or Schematic Diagram is.....
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An organised plan of the entire database that shows the tables, the fileds of the tables, and the relationships between them.
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What is the difference between Entities and Attributes in a schema?
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Entities are the Tables in a database. Attributes are the Fields in the tables.
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A relationship occurs when each record in the first entity (table) is related to exactly one record in the second entity (table)
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One-to-one
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A relationship 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).
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One-to-many
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A relationship 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).
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Many-to-many
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A type of access method used when accessing a storage medium such as magnetic tape.
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Sequential Access
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A type of access method used when accessing a storage medium such as magnetic disk, CD's or flash drives
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Direct Access
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A database that is located, stored, and maintained in a single location.
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Centralised Database
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A database located at more than one site that acts as a single collection of data, but is geographically dispersed.
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Distributed Database
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There are 6 relational operators used in SQL. What are they?
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Equal to =Not equal to <>Less than Less than and equal to <=Greater than and equal to >=
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What is Data Mining?
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It is the process of looking for trends in the data stored in databases. It discovers patternsthat 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 improvement in technology.
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Three generations of backup master files
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Grandfather - Oldest backupFather - Second Oldest bacjupSon - Newest backup
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Disadvantages of paper records
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Paper deteriorates over timeBulky to storeData cannot be altered or deleted easilyData can only be sorted by one field
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Describe Batch Transaction Processing
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Collects data in a group and processes at a later time.
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Describe Real Time Processing
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As data is collected, it is processed immediately, providing instant confirmation.
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Describe what a Decision Support System does
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Takes data from TPS, MIS and data from external sourcesto make decisions
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Name 5 different information technologies
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Networked Computers, Keyboards, Monitors, EFTPOS machines, Barcode Scanners, LAN/WAN, Printers, Photocopiers, Camera, Variety of software.
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Name 5 different office automation systems
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Word Processors, DBMS software, Voice Mail/E-mail, Scheduling Software, Spreadsheets, DTP software
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What are some advantages of computer- based information systems over manual systems?
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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.
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What is a DBMS
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Database Management system
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