How to Accurately Calculate Age as an Integer in MySQL?

Calculating Age as an Integer in MySQL

When determining the age of an individual based on their birth date stored in a MySQL database, the difference in days provided by the DATEDIFF() function falls short of providing an accurate integer representation. To overcome this challenge, a multi-step approach is required.

Step 1: Calculate the Years

The expression YEAR(CURDATE()) - YEAR(birth_date) yields the difference in years between the current date and the birth date. However, this approach does not account for incomplete years. For example, if the current date is May but the birth date is June, the individual's age is still 31.

Step 2: Correct for Incomplete Years

To address the incomplete year issue, the following subquery can be used:

(SELECT FLOOR((DAYOFYEAR(CURDATE()) - DAYOFYEAR(birth_date)) / 365.25))

This subquery calculates the number of years and days elapsed since the individual's birth date, taking into account leap years.

Step 3: Combine Results

The final expression to calculate age as an integer is:

(YEAR(CURDATE()) - YEAR(birth_date)) - (SELECT FLOOR((DAYOFYEAR(CURDATE()) - DAYOFYEAR(birth_date)) / 365.25))

This expression subtracts the incomplete years from the full number of years, resulting in an integer representing the individual's age.

Alternative Solution

Another option for calculating age as an integer in MySQL is to use the TIMESTAMPDIFF() function:

SELECT TIMESTAMPDIFF(YEAR, date_of_birth, CURDATE()) AS difference FROM student

This function directly calculates the difference in years between two timestamps, avoiding the need for complex calculations. It can also be used to calculate differences in months or days by replacing YEAR with MONTH or DAY.

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