In simple terms
A friendly intro before the formal notes — no formulas yet.
Keeping Data Correct
Data integrity is all about making sure that the data stored in a computer system is accurate, consistent, and trustworthy. It's not about keeping data secret, but about ensuring it hasn't been accidentally corrupted or entered incorrectly.
Imagine a library. The librarian's job is to ensure every book is on the correct shelf, has the right label, and all its pages are intact. This is data integrity – maintaining the correctness and order of the information. Data security, on the other hand, is like locking the library doors at night to prevent unauthorised people from getting in. Both are important, but they solve different problems.
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Data integrity means ensuring data is accurate and consistent. For example, a student's age must be a sensible positive number.
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Integrity is different from security. Integrity is about data quality (is it correct?), while security is about protection (is it safe from unauthorised access?).
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Validation is an automated check to see if data is reasonable before it's accepted. For instance, a system can validate that a postcode entry matches the UK format 'LLN NLL'.
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Verification is a check to ensure data has been copied correctly from one place to another. A common method is double entry, where you are asked to type your new password twice.
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Full topic notes
Formal explanation with the rigour you need for the exam.
Data Integrity vs. Data Security
It is crucial to distinguish between data integrity and data security, as they address different concerns. Data integrity is about the quality and reliability of the data itself. It aims to prevent accidental changes to data. Data security, in contrast, is about protecting data from unauthorised access and malicious intent. It aims to prevent deliberate, unauthorised changes or theft of data.
Integrity Focus: Accuracy, consistency, and completeness of data.
Security Focus: Confidentiality, availability, and protection against unauthorised access.
Example of Integrity Failure: A power outage corrupts a customer database file, making records unreadable.
Example of Security Breach: A hacker bypasses a firewall to steal the customer database file.
An employee accidentally typing the wrong price for a product is an integrity issue. An ex-employee logging in to deliberately change prices is a security issue.
Ensuring Integrity Part 1: Validation
Data validation is the process of using automatic checks, performed by the computer system, to ensure that data is sensible, reasonable, and plausible before it is accepted into the system. Validation can't confirm that the data is 100% correct, but it can reject many obvious errors at the point of entry.
Range Check: Ensures a number is within a specified lower and upper bound. E.g., an exam percentage must be between 0 and 100.
Format Check: Ensures data conforms to a predefined pattern. E.g., a date must be in DD/MM/YYYY format.
Length Check: Ensures data is a specific number of characters long, or within a min/max length. E.g., a mobile number must be 11 digits.
Presence Check: Ensures a field is not left empty. E.g., an email address field cannot be blank.
Type Check: Ensures data is of a specific data type. E.g., the 'Age' field must contain a number, not text.
Check Digit: An extra digit added to a number, calculated from the other digits. The computer can recalculate the check digit to validate the number's integrity. Commonly used in ISBNs for books and EAN/UPC barcodes.
Ensuring Integrity Part 2: Verification
Data verification is a process used to check that data has been accurately transcribed from a source medium to a computer system. Its sole purpose is to detect errors made during the manual process of typing data in. Unlike validation, verification often involves a human or a comparison of two data sets.
Double Entry: The data is entered twice, often by two different people or by the same person at different times. The computer system compares the two entries. If they do not match, an error is reported, and the user is prompted to correct it. This is common for password creation.
Visual Check (Proofreading): The user manually compares the data displayed on the screen with the original source document (e.g., a paper form). This relies on the user's concentration to spot any differences.
Examiners frequently ask for the difference between validation and verification. Remember: Validation is an automated check for sensible data (e.g., is the age between 0-120?). Verification is a check for transcription errors (e.g., did you type what you meant to type?). Be specific in your answers; 'a check' is too vague. Name the type of check, e.g., 'a range check' or 'double entry verification'.
Worked examples
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An ordering system uses 6-digit product codes. The 7th digit is a check digit calculated using the modulus-11 method with weights 7, 6, 5, 4, 3, 2. Calculate the check digit for the product code 830154.
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Multiply each digit by its corresponding weight:
A hospital clerk is entering a patient's National Health Service (NHS) number, 123 456 7890, from a paper form into a new database. The system rejects the entry.
(a) The NHS number is always 10 digits long. State the validation check that would have failed. (b) Describe a verification method the clerk could use to ensure they enter the number correctly on the second attempt.
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(a) Validation Check: A length check. The number entered, 1234567890, has 10 digits. However, the spaces mean the input string 123 456 7890 has a length of 12 characters. A strict length check expecting exactly 10 characters would fail. Alternatively, a format check expecting 10 numeric digits (NNNNNNNNNN) would also fail due to the spaces.
How it all connects
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Glossary
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Quick check
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Revision flashcards
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What is Data Integrity?
The maintenance of, and the assurance of the accuracy and consistency of, data over its entire life-cycle. It ensures data is correct, complete, and reliable.
Key takeaways
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Integrity Focus: Accuracy, consistency, and completeness of data.
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Security Focus: Confidentiality, availability, and protection against unauthorised access.
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Example of Integrity Failure: A power outage corrupts a customer database file, making records unreadable.
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Example of Security Breach: A hacker bypasses a firewall to steal the customer database file.
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An employee accidentally typing the wrong price for a product is an integrity issue. An ex-employee logging in to deliberately change prices is a security issue.
Practice — then mark it
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Test Your Knowledge on Data Integrity
Test Your Knowledge on Data Integrity
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Frequently asked
Checkpoint
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