Chapter 14. Maintaining Data Integrity

Terms you'll need to understand:

• DISABLE NOVALIDATE

• DISABLE VALIDATE

• ENABLE NOVALIDATE

• ENABLE VALIDATE

Concepts you'll need to master:

• Implement data integrity constraints.

• Maintain data integrity constraints.

• Obtain constraint information from the data dictionary.

Data integrity generally refers to the validity of data. Data integrity can be compromised in many different ways. Errors can be introduced when the data is entered or whenever the data is transmitted from one computer to another. Integrity can be compromised by software bugs, viruses, hardware malfunctions, or disk crashes. The introduction of invalid data can occur whenever a certain set of circumstances come together to create just the right conditions that would allow for the inaccuracies; and the inaccuracies might even mean that there are more copies of a given piece of information (such as a receipt or an invoice) than there should be at any given time.

This chapter deals with the manner in which Oracle enables you to avoid these inaccuracies. The first section defines what is meant technologically by data integrity with respect to Oracle databases and instances.