Data Types & Validation (Edexcel IGCSE ICT)

Data types

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

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