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Databases

Database security, integrity and recovery

  • 3 things to know
  • A2 Unit 1

Overview

Data integrity, four validation checks a database can apply and check digit.

What you need to know

Answer each one before you reveal it.

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Key term

What is validation, and what is it able to check?

Key term

What is verification, and how does it differ from validation?

Key term

Name four validation checks a database can apply.

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is data integrity?

    Model answer

    Data integrity is the accuracy and consistency of data over its whole life. Integrity is maintained by validation on entry, by referential integrity between tables, by transactions, and by controls that prevent unauthorised or accidental change.

  2. 2

    What is validation, and what is it able to check?

    Model answer

    Validation is an automatic check that data entered is reasonable and of the right kind. Validation can check a value is present, is the right type, is within a range, matches a format or appears in a list, but it cannot tell whether the value is actually correct.

  3. 3

    What is verification, and how does it differ from validation?

    Model answer

    Verification checks that data has been transcribed accurately, by double entry or by a visual check against the source. Validation asks whether a value is plausible; verification asks whether it is the value that was supplied.

  4. 4

    Name four validation checks a database can apply.

    Model answer

    A presence check requires a value; a range check requires it to fall between limits; a format or picture check requires a pattern such as two letters and six digits; and a lookup check requires the value to exist in a related table.

  5. 5

    What is a check digit?

    Model answer

    A check digit is an extra digit calculated from the others in a code and appended to it. When the code is entered the calculation is repeated, so a mistyped or transposed digit produces a mismatch and is rejected.

  6. 6

    How does access control protect a database?

    Model answer

    Access control gives each user an account with privileges limited to what their role requires, so an operator can enter orders without being able to alter prices, and every action can be traced to an individual.

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