Data Types & Validation (Edexcel IGCSE Ict)

Data types

Spec point — 6.2.1

What is a data type?

• A data type is the type of data that can be held in a field and is defined when designing a table in a database

• Examples of common datatypes are:

  • Numerical/number - whole/decimal numbers
  • Alphanumerical- contains letters & numbers
  • Date/Time
  • Boolean- true or false values
  • Currency

• In the car table below, the following datatypes would be used:

  • car_id: numerical
  • make: alphanumerical
  • model: alphanumerical
  • colour: alphanumerical
  • price: currency

cars

Validation

Spec point — 6.2.3

What is validation?

• Validation is used to check that an input from a user is acceptable and that it matches the requirements of the database

• There are 5 main categories of validation which can be carried out on fields and data types, these are:

  • Length check
  • Type check
  • Range check
  • Presence check

• There can be occasions where more than one type of validation will be used on a field

• An example of this could be a password field which could have a length, presence and type check on it

Length check

• Checks the length of an input
• An example is ensuring that a password is 8 or more characters in length

Type check

• Check the data type of a field
• An example is checking a user's age has been entered as an integer

Range check

• Ensures the data entered as a number falls within a particular range
• An example is checking a user's age has been entered and falls between the digits of 0-100

Presence check

• Looks to see if any data has been entered in a field
• An example is checking that a user has entered a name when registering for a website