MySQL: Find Missing Dates Between a Date Range

Question

I need some help with a mysql query. I\'ve got db table that has data from Jan 1, 2011 thru April 30, 2011. There should be a record for each date. I need to find out whethe

Answer 1

1. CREATE TABLE Days (day DATE PRIMARY KEY);

2. Fill Days with all the days you're looking for.

   mysql> INSERT INTO Days VALUES ('2011-01-01');
   mysql> SET @offset := 1;
   mysql> INSERT INTO Days SELECT day + INTERVAL @offset DAY FROM Days; SET @offset := @offset * 2;
   

   Then up-arrow and repeat the INSERT as many times as needed. It doubles the number of rows each time, so you can get four month's worth of rows in seven INSERTs.

3. Do an exclusion join to find the dates for which there is no match in your reports table:

   SELECT d.day FROM Days d 
   LEFT OUTER JOIN Reports r ON d.day = DATE(r.reportdatetime) 
   WHERE d.day BETWEEN '2011-01-01' AND '2011-04-30' 
       AND r.reportdatetime IS NULL;`