2.2 Programming V2

2.2 Programming V2

1. Subroutines

   • Procedures
     • Are called by their names
     • They do not return their values
   • Functions
     • Are called by assigning their return value to something
     • They always return a single value
   • Defines a large amount of coding into one value
     • Useful to reuse code faster
     • Good so work can be split between programmers

2. SQL (Standard Query Language)

   • Programming language used to work with databases
   • Can be run from a special window in a database package
   • SQL Keywords
     • SELECT
       • The variable you want to find
     • FROM
       • From which database
     • WHERE
       • Different columns
     • e.g. To find a SongTitle more than 3 mins long
       • SELECT SongTitle FROM Songs WHERE Length > 3

3. Iteration

   • The repetition of a process
   • For Counter (Counter-controlled)
     • Loops for a specific number of times, depending on the counter number
   • While Loop (Condition-controlled)
     • Better for user interfaces
     • Loops until the condition is met/changes

4. Data Types

   • integer
     • "for loop" or "while loop," an integer is used
   • Real
     • numbers that contain floating decimal points. For example, the numbers 5.5
   • Boolean
     • Statement that has a true or false answer
   • String
     • used to represent text rather than numbers
   • Array
     • organize data so that a related set of values can be easily sorted or searched

5. Variables

   • Identifier
     • Names of the variables within a program that are used to identify the relevant data/info
   • Input
     • indicates a user will be inputting something
   • Output
     • indicates that an output will appear on the screen
   • Assignment
     • statement in computer programming that is used to set a value to a variable name. The operator used to do assignment is denoted with an equal sign (=)
   • pseudocode
     • human reading rather than machine reading