​It is easy to make mistakes when entering data into a database. Database applications allow the user to set rules that automatically check the data to make sure that it is reasonable or sensible. This process is known as data validation.

Data validation rules are assigned to each field in a data table when the table is created.

Data that does not follow the rules for a particular field is rejected and an error message is displayed.

What is the data validation?

Types of validation check

Keywords

Validation: An automatic check to reduce the chance of errors being made when data is entered into a computer system.

Validation rule: A rule that specifies the characteristics of valid data item in a database field.

Error message: Information or instruction to help a user resolve a problem

Validation text: A message displayed when the data a user enters under a field heading in a database does not match the validation rules

for that field

How to use data validation: Presence check

1. ​Select the Name field by clicking on it.

2. Scroll down to the General properties for this field.

3. Select Validation Rule and Validation Text for the Name field as shown below

How to use data validation: ​Length check

Remember: A length check ensures that the correct number of characters is entered into a field. This could be a minimum or maximum number of characters that is acceptable, or a precise number of characters that is required for that field.

How to use data validation: Range check​

Remember: A range check ensures that data entered into a database falls within specific values.

How to use data validation: Type check​

Remember: Type check​ make sure that the user enters the correct type of data into a field, for example only digits are added to number fields or only text is added to a short text field.

Activity

You must create a database file and write a validation rule looking at the table