A data analyst needs to compute the number of days from dates in a flat file to the current date. What is the best approach?

• A. Validate the date format with logical functions and use date functions to analyze.
• B. Use date functions to analyze the data with no conversion.
• C. Convert data to date format and use date functions.
• D. Transform data to a numerical value and use mathematical functions.

Answer: (C)

Dates stored in a flat file are usually text. To reliably compute the number of days between each date and today, you need to convert those strings into a date data type first. Once the data are real dates, you can use date arithmetic to find the difference between each date and the current date, which yields the number of days. Relying on validation alone may catch bad formats, but it doesn’t enable accurate arithmetic until the values are cast to dates. Converting to date format then applying date functions gives correct, consistent results across all rows and handles the actual day-count calculation cleanly.