Tuesday, February 8, 2011
Organisation Methods & Appropriate Field Data Types @ 5:43 PM
~Organisation Methods & Appropriate Field Data Types~
Page 119-122 of textbook
Computer Based Methods of Organising
Flat File Databases- The simplest form of database where most non-computer databases are examples of flat file databases (e.g. telephone books)
Relational Databases- Used extensively as the data store for all types of applications.
Hypertext/Hypermedia- Based on the connection of related data using hyperlinks (e.g. the World Wide Web)
Choosing an Appropriate Field Data Type
Decisions between text and numeric:
- Arithmetic operations (addition, subtraction, multiplication,etc) - NUMERIC
- Date/Time (no mathematical operations) - DATE/TIME
- Sorting data alphabetically and numerically where numbers are entered into the text field and sorted alpha-numerically (e.g. 1, 10, 103, 12, 2, 21, 245, 5)
If text data is required:
- Limit of characters where TEXT holds 255 characters whilst MEMO holds almost unlimited
- Unicode or ASCII, where Unicode is an extension of ASCII that includes foreign language characters and symbols
If numeric data is required:
- Will values stored always be integers (whole numbers). Integers are best used if so and use the least amount of storage
- Consider the range of values required
- Currency or money values and which is optimised for the highest level of financial calculations (e.g. Banker's Rounding)
- How precisely the data can be represented as a floating point which specifies the number of decimal points (rarely used and doesn't represent as accurately due to limited representation) and floating which uses any number of decimal (commonly used with more range that's more versatile with up to 7 significant figures)
Tuesday, February 8, 2011
Organisation Methods & Appropriate Field Data Types @ 5:43 PM
~Organisation Methods & Appropriate Field Data Types~
Page 119-122 of textbook
Computer Based Methods of Organising
Flat File Databases- The simplest form of database where most non-computer databases are examples of flat file databases (e.g. telephone books)
Relational Databases- Used extensively as the data store for all types of applications.
Hypertext/Hypermedia- Based on the connection of related data using hyperlinks (e.g. the World Wide Web)
Choosing an Appropriate Field Data Type
Decisions between text and numeric:
- Arithmetic operations (addition, subtraction, multiplication,etc) - NUMERIC
- Date/Time (no mathematical operations) - DATE/TIME
- Sorting data alphabetically and numerically where numbers are entered into the text field and sorted alpha-numerically (e.g. 1, 10, 103, 12, 2, 21, 245, 5)
If text data is required:
- Limit of characters where TEXT holds 255 characters whilst MEMO holds almost unlimited
- Unicode or ASCII, where Unicode is an extension of ASCII that includes foreign language characters and symbols
If numeric data is required:
- Will values stored always be integers (whole numbers). Integers are best used if so and use the least amount of storage
- Consider the range of values required
- Currency or money values and which is optimised for the highest level of financial calculations (e.g. Banker's Rounding)
- How precisely the data can be represented as a floating point which specifies the number of decimal points (rarely used and doesn't represent as accurately due to limited representation) and floating which uses any number of decimal (commonly used with more range that's more versatile with up to 7 significant figures)
