Which function should be used to set PeriodDate to the first day of the month from OrderDate?

• A. Date Bucket
• B. Date Part
• C. Date From Parts
• D. Date Trunc

Answer: (D)

To set a date to the first day of its month, you truncate the date to the month. Truncating to month takes the OrderDate and snaps it to the start of that calendar month, giving you the first day (and typically midnight) of that month. For example, OrderDate of 2023-07-15 becomes 2023-07-01. This approach is the most direct and reliable because it preserves the year and month while resetting the day, without needing to piece together a new date from components or categorize dates into buckets. Other methods either return just parts of the date (like year or month as numbers) or require constructing a new date from year, month, and day, which is more verbose and error-prone for this specific goal.