MySQL sort multiple date columns

Question

I have a database with 3 key fields

• start_date
• end_date
• date

start_date and end_date are for events that will span multiple dates. date is for a single day event.

How can I sort all dates by start date OR date, whichever applies. Assume there is a 4th field, multiple_day_event , which is either "yes" or "no".

Answer 1

SELECT IF(multiple_day_event, start_date, date) AS mdate ORDER BY mdate

Answer 2

Well, it looks like IFNULL(START_DATE,DATE) IF(MULTIPLE_DAY_EVENT='yes',START_DATE, DATE) Or case, when :

CASE multiple_day_event
    WHEN 'yes' THEN START_DATE
    -- WHEN 'taco' THEN 'salsa???' Or any other when.
    ELSE DATE
END CASE