PL-300 DATESINPERIOD Practice Question

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

• ✗

  CALCULATE(SUM(Sales[Amount]), DATESBETWEEN('Date'[Date], MAX('Date'[Date]) - 365, MAX('Date'[Date])))

  Why it's wrong here

  This approach uses DATESBETWEEN with a fixed 365-day subtraction from MAX('Date'[Date]), which is problematic because it treats a year as exactly 365 days and ignores the extra day in leap years. On leap years (or when the period spans a leap day), the calculation will drift by one day, causing the window to start on the wrong date and potentially include or exclude a day's sales. DATESINPERIOD with MONTH handles varying month lengths and leap years cleanly by working at month granularity.

• ✓

  CALCULATE(SUM(Sales[Amount]), DATESINPERIOD('Date'[Date], MAX('Date'[Date]), -12, MONTH))

  Why this is correct

  DATESINPERIOD is the correct time-intelligence function here because it returns a contiguous interval ending at MAX('Date'[Date]) and extending back 12 full calendar months, respecting month boundaries rather than fixed day counts. With -12 and MONTH, the filter context established by CALCULATE adjusts the Sales[Amount] summation to include exactly the trailing 12 months relative to the latest visible date, which is exactly what a rolling 12-month total requires.

• ✗

  TOTALMTD(SUM(Sales[Amount]), 'Date'[Date])

  Why it's wrong here

  TOTALMTD is a month-to-date aggregator: it sums Sales[Amount] only from the beginning of the current month through the last visible date in the current filter context. This yields a partial-month cumulative figure that resets every month, so it cannot produce a 12-month rolling total. To capture a trailing year, you need a filter that spans multiple months, not just the current month's elapsed days.

• ✗

  CALCULATE(SUM(Sales[Amount]), DATESYTD('Date'[Date]))

  Why it's wrong here

  DATESYTD evaluates the year-to-date total, meaning it sums Sales[Amount] from only January 1 through the last visible date in the current year, depending on the year-end date set in the date table. This is a calendar-year cumulative measure, not a rolling 12-month measure, because the start point resets every January 1 rather than following a trailing window based on the current filter context. Therefore it will not reflect the last 12 months from any arbitrary date.

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