Data Processing Data Quality and Validation 2 — Questions and Answers
Question 1: What is referential integrity in a relational database?
- Ensuring column names follow naming conventions
- Ensuring foreign key values always reference existing primary key values (Correct answer)
- Compressing reference tables for performance
- Encrypting keys in lookup tables
Correct answer: Ensuring foreign key values always reference existing primary key values
Referential integrity ensures that foreign key values in one table always match existing primary key values in the referenced table.
Question 2: What is the purpose of a checksum in data validation?
- To speed up data retrieval
- To detect errors or corruption in transmitted or stored data (Correct answer)
- To compress large files before transfer
- To sort records in ascending order
Correct answer: To detect errors or corruption in transmitted or stored data
A checksum is a computed value derived from data that is compared after transmission or storage to detect any corruption or tampering.
Question 3: What is data consistency in data processing?
- All data is stored in the same file format
- Data is the same across all systems and does not contradict itself (Correct answer)
- All queries return results in under 100 ms
- All records have the same number of columns
Correct answer: Data is the same across all systems and does not contradict itself
Data consistency means the same data entity shows the same values across all systems and datasets, with no conflicting information.
Question 4: Which process automatically corrects or standardizes data to meet quality standards?
- Data archiving
- Data cleansing (Correct answer)
- Data partitioning
- Data replication
Correct answer: Data cleansing
Data cleansing identifies and corrects errors, inconsistencies, and formatting issues to improve overall data quality.
Question 5: What is a null value in a database?
- A value of zero
- The absence of any value — unknown or missing data (Correct answer)
- A negative integer
- An encrypted placeholder
Correct answer: The absence of any value — unknown or missing data
NULL represents the absence of a value in a field — it is different from zero or an empty string and means the data is unknown or missing.
Question 6: What is timeliness as a data quality dimension?
- How quickly queries execute
- Whether data is available and up-to-date when needed (Correct answer)
- Whether all columns have index coverage
- Whether data is stored in the correct timezone
Correct answer: Whether data is available and up-to-date when needed
Timeliness measures whether data is current and available within the required time frame when it is needed for decision-making.
Data Processing Data Quality and Validation 2
What is referential integrity in a relational database?