Mastering Timestamps: 3 Solutions to Calculate Duration in SQL

Calculating the Difference Between Two Timestamps

In the world of data management, timestamps play a critical role in understanding events that occurred at specific points in time. Timestamps record the date and time when a particular event happened, such as the time you placed an order on your favorite online store or the date you made a payment for your monthly bills.

Timestamps also help you understand the duration between two events, which is an essential feature in many data analyses. There are several common solutions you can use to calculate the difference between two timestamps accurately.

1) Solution 1: Difference in days, hours, minutes, and seconds

One way to calculate the duration between two timestamps is by computing the difference in days, hours, minutes, and seconds. You can accomplish this using the INTERVAL function.

For example, consider the following query:

``````SELECT TIMESTAMP '2021-09-01 10:00:00' AS start_time,
TIMESTAMP '2021-09-02 12:30:00' AS end_time,
EXTRACT(DAY FROM (end_time - start_time)) AS days,
EXTRACT(HOUR FROM (end_time - start_time)) AS hours,
EXTRACT(MINUTE FROM (end_time - start_time)) AS minutes,
EXTRACT(SECOND FROM (end_time - start_time)) AS seconds;``````

This query calculates the difference between the start time and end time in days, hours, minutes, and seconds.

2) Solution 2: Difference in years, months, days, hours, minutes, and seconds

Another way to calculate the duration between two timestamps is by using the AGE function.

This function computes the difference between two timestamps in years, months, days, hours, minutes, and seconds. For example, consider the following query:

``````SELECT TIMESTAMP '2021-09-01 10:00:00' AS start_time,
TIMESTAMP '2021-11-01 12:30:00' AS end_time,
AGE(end_time, start_time) AS duration;``````

This query calculates the difference between the start time and end time in years, months, days, hours, minutes, and seconds.

3) Solution 3: Difference in seconds

A third way to calculate the duration between two timestamps is by computing the difference in seconds. You can use the EPOCH function to accomplish this task.

For example, consider the following query:

``````SELECT TIMESTAMP '2021-09-01 10:00:00' AS start_time,
TIMESTAMP '2021-09-02 12:30:00' AS end_time,
EXTRACT(EPOCH FROM (end_time - start_time)) AS seconds;``````

This query calculates the difference between the start time and end time in seconds.

The Travel Table Example

Let’s consider a specific use case for calculating the duration between two timestamps. Suppose you have a travel table that records the details of a person’s travel, including the travel id, departure time, and arrival time.

Using the solutions we just discussed, you can quickly compute the duration of each travel. For example, consider the following travel table:

id departure arrival
1 2021-09-01 10:00:00 2021-09-01 12:30:00
2 2021-09-01 14:00:00 2021-09-01 17:00:00
3 2021-09-02 10:00:00 2021-09-02 12:30:00

You can use Solution 1 to calculate the duration of each travel in days, hours, minutes, and seconds:

``````SELECT id,
departure,
arrival,
EXTRACT(DAY FROM (arrival - departure)) AS days,
EXTRACT(HOUR FROM (arrival - departure)) AS hours,
EXTRACT(MINUTE FROM (arrival - departure)) AS minutes,
EXTRACT(SECOND FROM (arrival - departure)) AS seconds
FROM travel;``````

This query produces the following result:

id departure arrival days hours minutes seconds
1 2021-09-01T10:00:00.000Z 2021-09-01T12:30:00.000Z 0 2 30 0
2 2021-09-01T14:00:00.000Z 2021-09-01T17:00:00.000Z 0 3 0 0
3 2021-09-02T10:00:00.000Z 2021-09-02T12:30:00.000Z 0 2 30 0

Alternatively, you can use Solution 2 to calculate the duration of each travel in years, months, days, hours, minutes, and seconds:

``````SELECT id,
departure,
arrival,
AGE(arrival, departure) AS duration
FROM travel;``````

This query produces the following result:

id departure arrival duration
1 2021-09-01T10:00:00.000Z 2021-09-01T12:30:00.000Z “00 years 00 mons 00 days 02:30:00”
2 2021-09-01T14:00:00.000Z 2021-09-01T17:00:00.000Z “00 years 00 mons 00 days 03:00:00”
3 2021-09-02T10:00:00.000Z 2021-09-02T12:30:00.000Z “00 years 00 mons 00 days 02:30:00”

Finally, you can use Solution 3 to calculate the duration of each travel in seconds:

``````SELECT id,
departure,
arrival,
EXTRACT(EPOCH FROM (arrival - departure)) AS seconds
FROM travel;``````

This query produces the following result:

id departure arrival seconds
1 2021-09-01T10:00:00.000Z 2021-09-01T12:30:00.000Z 9000
2 2021-09-01T14:00:00.000Z 2021-09-01T17:00:00.000Z 10800
3 2021-09-02T10:00:00.000Z 2021-09-02T12:30:00.000Z 9000

In conclusion, calculating the duration between two timestamps is a crucial task in data management.

By using the solutions we discussed in this article, you can accurately compute the difference between two timestamps in days, hours, minutes, seconds, years, months, and seconds. In addition, we showed you how to apply these solutions to a specific use case involving a travel table.

With this knowledge, you are well on your way to becoming a proficient data analyst capable of handling complex date and time problems.