MYSQL Date Time Round To Nearest Hour

Question

I have a date time field in a MySQL database and wish to output the result to the nearest hour.

e.g. 2012-04-01 00:00:01 should read 2012-04-01 00

Answer 1

I think this is the best way, since it also will use the least amount of resources-

date_add(date(date_completed), interval hour(date_completed) hour) as date_hr

Answer 2

Update: I think https://stackoverflow.com/a/21330407/480943 is a better answer.

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You can do it with some date arithmetic:

SELECT some_columns,
    DATE_ADD(
        DATE_FORMAT(the_date, "%Y-%m-%d %H:00:00"),
        INTERVAL IF(MINUTE(the_date) < 30, 0, 1) HOUR
    ) AS the_rounded_date
FROM your_table

Explanations:

• DATE_FORMAT: DATE_FORMAT(the_date, "%Y-%m-%d %H:00:00") returns the date truncated down to the nearest hour (sets the minute and second parts to zero).

• MINUTE: MINUTE(the_date) gets the minute value of the date.

• IF: This is a conditional; if the value in parameter 1 is true, then it returns parameter 2, otherwise it returns parameter 3. So IF(MINUTE(the_date) < 30, 0, 1) means "If the minute value is less than 30, return 0, otherwise return 1". This is what we're going to use to round -- it's the number of hours to add back on.

• DATE_ADD: This adds the number of hours for the round into the result.