comp sci

• Static data structure


  A data structure with a fixed size
• Dynamic data structure


  a data structure that grows and shrinks as needed
• ['Sam','Lucy'] - what type of data structure

  1d array (1 dimensional)
• Is a 1d array typically static or dynamic


  Static
• Record


  Set of data about a single entity
• Can a record have multiple data types

  Yes
• Persistent relational database


  Permanent
• Organised relational database


  Data stored in records and fields
• What is an entity?

  Something in the real world to store data about
• What is an attribute


  Characteristics about an entity
• What software does databases require


  Handling software
• What is handling software


  Software that allows for the data base to be creates, the data retrieved , updates and deleted (CRUD)
• What is a table (comp sci)


  The whole table /all the data
• What is a field

  A column/variable
• What is a field name


  Name of the file
• What do applications that use databases use


  Database management system
• How does the database management system connect


  Applications > DMBS> File system > Database
• What does the DBMS ensure?


  That applications use data correctly, so not to compromise integrity of the database, code of programs are store on in it locations
• Other features of Databas management system


  - allows many applications to have access to data at once

  - contains access to data

  - provides backups

  - uses many languages and can alter structure of data

  - stops damage to the relationships between tables of data
• What is a flat file database?


  A database in which all the data is stored in a single table
• What is a relational database?


  A database with multiple entities, and data redundancy - not effective
• What is a one to one relationship with example

  A one to one relationship is if do entities connect but only once with each other so one item can only be bought by one person
• What is a one to many relationship with example?

  One to many is one one entity can connect to more than one of another entity so one item can be bought by multiple people
• What is a many-to-many relationship with an example?

  Many to many is when many of an entity can connect with multiple of another entity so an item can be bought by multiple people and someone can buy multiple items
• What happens to many to many relationships?

  Must be removed as too insefficieny
• How do relayional databases connect


  With keys and relationsips(e.g. one to one)
• 3 key fields


  Primary key, secondary key and foreign kwy
• What is the primary key


  (Pk) unique identifier of each table typically an ID number
• What is a secondary key?


  More than one field that could be a unique identifier
• What is a foreign key?


  A primary key from another table
• What is querying


  Searching for information from a database
• What is a benefit of databases?


  Allow for data to be retrieved, updated and filtered quickly using forms and queries
• What is validation within data

  Checks if the day within the table is valid
• What is an input mask


  Ensure inputted data follows a specific format
• Structure of relationship in the Operaring system?


  User - application - operating system

  - hardware

  - kernel

  - CPU

  - Memory

  - Devices
• What are the 6 types of operating systems?

  Distributed Os

  Embedded Os

  Multi tasking Os

  Multi user Os

  Real time Os

  Batch Os
• What is a distributed OS


  It computers multiple computers and spreads tasks up to improve efficiency
• What is an embedded OS


  Designed for a single device to have a limited range of jobs such as a dishwasher
• What is a multi tasking OS


  Typically for home pcs as it can cope with multiple programs at once
• What is a multi user OS


  Allows many different users to make use of a computer system and its resources at the same time.