You have a field storing the date of birth. Here I demonstrate how to calculate the age.
DATEDIFF(CURRENT_DATE, STR_TO_DATE(your_field_here, '%Y-%m-%d'))/365 AS AgeWithDecimals
DATE_FORMAT(FROM_DAYS(DATEDIFF(now(),your_field_here)), '%Y')+0 AS AgeWihoutDecimals
...
https://www.youtube.com/watch?v=hHyEcWLn5AY