Databases Flashcards
What does organised mean in databases?
Databases have a structure so that they can easily be processed.
What does a database need to be to be functional?
- Accurate
- Up to date
- Available for those who need to use them
- Protected from those who should not have access to them
What should databases be protected against?
- Errors
- Loss
- Insufficient data
- Inconsistencies
- Unauthorised access
What can errors in databases result in?
- Embarrassment, sending bills to dead customers.
- Financial loss, if a bank account is wrongly credited.
- Life or death situations, such as incorrect navigational data for aircraft.
Why can data be lost?
- A catastrophe, such as fire or flood.
- An accident, such as an employee.
- Malicious action, such as by an intruder.
How can data be protected by potential loss?
- Making regular backups
- Having a mirror database so that the data is saved in at least two places
- Storing backups in a safe place such as in the cloud or otherwise off site
- Restricting access
- Keeping audit trails of who has accessed data
What is data integrity?
It means the data reflects reality and implies the data is correct and fit for purpose.
What can data integrity be maximised by?
- Suitable validation
- Software that prevents inconsistent states
What is validation?
It checks the data conforms to certain rules.
Name two examples of validation methods?
- Length check
- Type check
- Range check
- Presence check
- Lookup check
- Format check
- Check digit
What is the meaning of a length check? Give an example.
Must have a certain number of characters or be above or below some limits.
E.g. A password must be long enough to be strong.
Name a validation method, what do it means and give an example.
Look it up in your book nerd. I’m to lazy to type them all out. Here is some methods:
- Length check
- Type check
- Range check
- Presence check
- Lookup check
- Format check
- Check digit
What does persistent mean?
It is saved on secondary storage for the future.
