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. Operators

   • Arithmetic Operators
     • / - Division
     • * - Multiplication
     • + - Addition
     • - - Subtraction
     • MOD - Modulus (Remainder) e.g.12 MOD 5 = 2
     • DIV - Ouotient e.g. 17 DIV 5 = 3
     • ^ - Exponentiation (To the power of)
   • Represents the operations that are performed on the data
     • Logical Operators (Only used in Booleans)
       • AND - Two conditions must be met for the statement to be true
       • OR - At least one condition must be met for the statement to be true
   • String Operators
     • .length - Number of characters in a string (including spaces)
     • .lower - lowercase
     • .upper - UPPERCASE
     • .substring (x,y) - Part of a string
   • Comparison Operators
     • != - Not equal to
     • == - Equal to
     • < - Less than
     • > - Greater than
     • <= - Less than or equal to
     • >= - Greater than or equal to

5. data types

   • integer
     • whole number
   • real
     • decimal places
   • boolean
     • true or false
   • string
     • words

6. arrays

   • a table
   • 2D array
     • rows
     • columns
     • holds data