MySQL Cookbook

Breaking Down Time Intervals into Components

Problem

You have a time interval represented as a time, but you want the interval in terms of its components.

Solution

Decompose the interval with the HOUR( ), MINUTE( ), and SECOND( ) functions. If the calculation is complex in SQL and you’re using the interval within a program, it may be easier to use your programming language to perform the equivalent math.

Discussion

To express a time interval in terms of its constituent hours, minutes, and seconds values, calculate time interval subparts in SQL using the HOUR( ), MINUTE( ), and SECOND( ) functions. (Don’t forget that if your intervals may be negative, you need to take that into account.) For example, to determine the components of the intervals between the t1 and t2 columns in the time_val table, the following SQL statement does the trick:

mysql> SELECT t1, t2,
    -> SEC_TO_TIME(TIME_TO_SEC(t2) - TIME_TO_SEC(t1)) AS 'interval as TIME',
    -> IF(SEC_TO_TIME(TIME_TO_SEC(t2) >= TIME_TO_SEC(t1)),'+','-') AS sign,
    -> HOUR(SEC_TO_TIME(TIME_TO_SEC(t2) - TIME_TO_SEC(t1))) AS hour,
    -> MINUTE(SEC_TO_TIME(TIME_TO_SEC(t2) - TIME_TO_SEC(t1))) AS minute,
    -> SECOND(SEC_TO_TIME(TIME_TO_SEC(t2) - TIME_TO_SEC(t1))) AS second
    -> FROM time_val; +----------+----------+------------------+------+------+--------+--------+ | t1 | t2 | interval as TIME | sign | hour | minute | second | +----------+----------+------------------+------+------+--------+--------+ | 15:00:00 | 15:00:00 | 00:00:00 | + | 0 | 0 | 0 | | 05:01:30 ...