How to calculate age using the date and time functions in MySQL

Key takeaways:

• Calculate age dynamically using date functions instead of storing it statically.

• Simple year subtraction may overestimate age; use TIMESTAMPDIFF() for precise calculations.

• UTC storage stores dates in UTC format to avoid time zone issues and ensure consistency.

Calculating age from date of birth (DOB) is a common task in various applications, including user profiles, demographic analysis, and generating reports. MySQL provides several date and time functions that help compute age efficiently. Since age changes annually and cannot be stored statically without frequent updates, it is more practical to calculate it dynamically using date and time functions.

Calculating age with date and time functions

Let’s start by exploring the basic methods for calculating age from date of birth using SQL. We’ll also look at how to improve accuracy with precise calculations and how to handle time zone challenges.

Simple age calculation

A common method to calculate age is to subtract the birth year from the current year. Let’s have a look at the following query:

Explanation:

The explanation of the above code is as follows:

• Lines 1–2: We retrieve EmpID and EmpName from the Employees table. We calculate the age by subtracting the year of the DateOfBirth from the current year YEAR(CURDATE()), and label this calculation as Age.

• Line 3: The data is retrieved from the Employees table.

Please note that this approach is straightforward but may not provide an accurate age. For example, if an employee’s birthday hasn’t occurred yet this year, this method will overestimate their age. Let’s consider the age calculation for Alexa. Let’s say the CURDATE() is August 12, 2024, and the DateOfBirth for the specific employee is September 22, 1990. Let’s see how the difference is calculated:

The results can be inaccurate because Alexa’s birthday has not yet occurred this year. This calculation returns an age of 34, but since her birthday is later in the year, her actual age is still 33. The formula doesn’t consider whether the birthday has happened yet this year, which can lead to an overestimation of age.

Accurate age calculation

To improve accuracy, calculate the exact age by considering both the birth date and the current date. Here’s a more precise method:

Explanation:

The explanation of the above code is as follows:

• Lines 1–2: We retrieve all the columns from the Employees table. We calculate the age of each employee by finding the number of days between their DateOfBirth and the current date NOW() using TIMESTAMPDIFF(), dividing by 365 to get the approximate number of years, and then using FLOOR() to round down to the nearest whole number. The result is labeled as Age.

• Line 3: The data is retrieved from the Employees table.

Note: The function TIMESTAMPDIFF(unit, datetime_expr1, datetime_expr2) takes three arguments:

• unit: Specifies the unit of time for the difference (e.g., days, months).

• datetime_expr1 and datetime_expr2: The two datetime expressions to compare, with datetime_expr1 being subtracted from datetime_expr2.

Managing timezone challenge

Timezone differences can affect date calculations, especially in applications with global users. It’s best to store dates in UTCCoordinated Universal Time format to ensure consistency and avoid time zone issues. Let’s have a look at the code below:

This query provides the current date and time in UTC. It helps streamline our data processing and minimize potential issues when converting between different time zones. As a best practice, convert to the local time zone only when displaying data to users. Let’s see a code example where we calculate the age using UTC_TIMESTAMP():

Explanation:

The explanation of the above code is as follows:

• Lines 1–2: We retrieve all the columns from the Employees table. This query uses TIMESTAMPDIFF() to determine the number of days between the date of birth and the current date (UTC_TIMESTAMP()), then divides by 365 to approximate the age. The FLOOR function ensures the result is an integer, representing the full years lived. The result is labeled as Age.

• Line 3: The data is retrieved from the Employees table.

Quiz

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Conclusion

We explored how to calculate age using MySQL’s date and time functions. We started with basic age calculations, moved to more accurate methods, and discussed the challenge of managing time zones. In summary, having age calculations at runtime saves space, keeps the information accurate, and easily adjusts to different age needs without having to constantly update the data. We should store dates in UTC to keep things consistent and simple and only convert to local time when needed.