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J276/02 - Section 5 - Programming (Storing Data (Databases organise data…

- - - - 2 bytes or 4 bytes.
    - - 4 bytes or 8 bytes.
    - - 1 bit is needed but 1 byte is usually used.
    - - 1 byte.
    - - 1 byte for every character in the string.
- - - - CONST pressure as INT = 30
      - VAR temperature as REAL = 20.5
      - VAR weight as REAL
      - CONST pressure = 30
      - REAL temperature = 20.5
      - REAL weight
- - - - x.length - returns the number of characters in string x.
      - x.lower - changes all characters in string x to lower case.
      - x[i] - extracts the character in position i from string x.
      - x.upper - changes all characters in string x to upper case.
      - x.subString(a, b) - extracts a string starting at position a with length b from string x.
- - - - Keep going while the condition is true.
      - Never runs the code inside it if the condition is initially false.
      - Controlled by a condition at the start of the loop.
      - You get an infinite loop if the condition is always true.
    - - Keep going while the condition is true.
      - Always runs the code inside it at least once.
      - Controlled by a condition at the end of the loop.
      - You get an infinite loop if the condition is always true.
    - - Keep going until the condition is true.
      - Always runs the code inside it at least once.
      - Controlled by a condition at the end of the loop.
      - You get an infinite loop if the condition is never true.
- - - - This can be done by using the name of the array and the element's position/
    - - Done by reassigning the array position to a different data value.
    - - ARRAY rowers[4] creates the array 'rowers' and makes it size 4.
- - - - openRead - file opened in read mode.
      - openWrite - file opened in write mode.
- - - - Functions are similar the main difference is that they always return a value, procedures don't.
    - - Parameters - special variables used to pass values into a sub program. For each one you can specify a name, data type and a default value.
      - Arguments - the actual values that the parameters take when the sub program is called.
- - - - SQL is a structured query language that can be used to create, update and query (search) databases. It consists of standard commands called statements.
    - - Field - A category of information.
      - Wildcard - Represents all data values.
      - Record - A completed set of fields for one data entry.
      - Boolean Operator - Work with Boolean values, AND, OR and NOT
      - Table - A set of records for one entity..
      - SCRUD
        
        Search
        
        Create
        
        Read
        
        Update
        
        Delete
      - Database - a collection of data bases represented as tables.
      - Command Words
        
        Where - Allows you to filter results set to include only certain rows.
        
        Like - Used with WHERE to search for a specific pattern.
        
        Select - Used to fetch data from a database.
        
        Order by - Indicates how you went to sort the results.
        
        Distinct - Returns only different values.
        
        Limit - Can specify the maximum number of rules two results set will have.
        
        Count - Takes the name of a Colum as an argument and counts the no-grow where the Colum is not NULL
      - SQL - Structured query language, is used to search tables for specific data. It uses functions such as SCRUD and Boolean operators. Also not case sensitive.