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Data, Information and Data Representation

Validation: format checks and lookup checks

  • 3 things to know
  • AS Unit 2

Overview

Format check, lookup check and risk of making validation rules too strict.

What you need to know

Answer each one before you reveal it.

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Key term

Why are several validation checks usually applied to a single field?

Key term

What is a format check?

Key term

Which pattern would a format check apply to a date entered as day, month and year?

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is a format check?

    Model answer

    A format check confirms that an entry follows a set pattern of letters, digits and punctuation laid down for that field.

  2. 2

    Which pattern would a format check apply to a date entered as day, month and year?

    Model answer

    A date field can be checked against a pattern of two digits, a separator, two digits, a separator and four digits.

  3. 3

    Give an example of a format check applied to a vehicle registration.

    Model answer

    A registration can be checked against a pattern of two letters, two digits, a space and three letters, so an entry with the letters and digits in the wrong positions is refused.

  4. 4

    Why is a format check sometimes called a picture check?

    Model answer

    The required pattern is written out as a picture of the entry, with a symbol standing for each allowed character position, and the check compares what was typed against that picture.

  5. 5

    What is a lookup check?

    Model answer

    A lookup check confirms that an entry appears in a stored list or table of acceptable values, and refuses anything that is not on the list.

  6. 6

    Give an example of a field well suited to a lookup check.

    Model answer

    A county field is well suited to a lookup check, because only the recognised county names are acceptable and every one of them can be held in a table.

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