MySQL date comparisons returning different results

Question

I have a query selecting rows between dates.

SELECT * FROM `table` WHERE statusDate >= '2014-10-01' AND statusDate <= '2014-10-31'

When I use the above query it returns significantly less rows than the following query...

SELECT * FROM `table` WHERE statusDate > '2014-09-30' AND statusDate < '2014-11-01'

Technically I'd have thought it would return the same results but it's not.

My understanding on the bottom query is that it selects from dates above and below the dates stated, not including. Why would the results be different?

Answer 1

If statusDate is a DATETIME column, the time of day will cause the results to be different for rows on the last day of the month. When you convert the date 2014-10-31 to a DATETIME , it's 2014-10-31 00:00:00 . If there's a row whose statusDate is 2014-10-31 09:23:11 , it will not be selected by the first query, but it will be selected by the second query.

You can solve this by using:

WHERE statusDate >= '2014-10-01' AND DATE(statusDate) <= '2014-10-31'

or you can add the time to the WHER clause:

WHERE statusDate >= '2014-10-01' AND statusDate <= '2014-10-31 23:59:59'