How to Calculate Datetime Differences in MySQL Using TIMESTAMPDIFF?

Calculating Datetime Differences in MySQL

When working with datetime values in MySQL, calculating the difference between two dates and times becomes a common task. For this purpose, MySQL provides a powerful function called TIMESTAMPDIFF.

Query for Datetime Difference:

To find the difference between two datetimes, use the following syntax:

SELECT TIMESTAMPDIFF(unit, datetime1, datetime2)

Example:

Consider the scenario where you have a table storing the last login time of users as a datetime column named last_login. To calculate the time elapsed since the last login, you can use the following query:

SELECT TIMESTAMPDIFF(SECOND, last_login, NOW())

In this query, last_login represents the field containing the last login time, while NOW() represents the current date and time. The TIMESTAMPDIFF function calculates the difference between these two datetimes in seconds.

Unit of Measurement:

The unit parameter in the TIMESTAMPDIFF function specifies the unit of measurement for the difference. Some common units include:

• SECOND
• MINUTE
• HOUR
• DAY
• MONTH
• YEAR

Choose the appropriate unit based on the context of your application.

Additional Options:

• Absolute Value: To ensure the difference is always positive, use the ABS() function before the TIMESTAMPDIFF function.
• Zero Coalescing: Use the COALESCE() function to replace null values with a specific value before using TIMESTAMPDIFF.

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