How does MySQL calculate the time difference between two times?

In MySQL, you can use the TIMESTAMPDIFF function to calculate the time difference between two timestamps. Here is an example:

SELECT TIMESTAMPDIFF(SECOND, start_time, end_time) AS time_diff
FROM your_table;

In the example above, start_time and end_time are the two time columns you want to calculate the time difference between. The first parameter of the TIMESTAMPDIFF function is the unit of time (e.g. SECOND for seconds, MINUTE for minutes, HOUR for hours, etc.), the second parameter is the earlier time, and the third parameter is the later time. In the query above, we chose to use SECOND as the unit of time to calculate the time difference.

The query results will include a column called time_diff, which represents the time difference between two times in seconds. You can choose a different time unit as needed to calculate the time difference.