Q153 - DATEDIFF vs. Subtracting Two Dates

Hi Leon - I believe the solution here may be incorrect due to the issue of how MySQL calculates dates as you previously mentioned in this thread.

This query:

SELECT project_id,
               DATEDIFF(end_date, start_date) AS datediff_calc,
               (end_date - start_date) AS simple_subtraction
  FROM project_detail;

produces the following table:

The solution is calculating on the simple_subtraction coluimn, but I believe it should be calculating on the datediff_calc column.

Thanks!

Will