Question

I am trying to implement a procedure within mysql that returns the age based on a calculation.
The date of birth (DATE) is passed in and then the calculation is done. Should be relatively straight forward but I cannot seem to get it to work. I am not sure if this is an appropriate situation for a “select statement” and
I apologize if this is extremely simple but this is my first run at procedures.

If somebody could please tell me what I am doing wrong, it would be much appreciated.

Thanks!

P.S. I have a table called “PERSON” that contains the field “age” (int) which is currently empty until the stored procedure is called.

DELIMITER $$
CREATE PROCEDURE determineAge(IN birthDate DATE)
BEGIN
DECLARE today TIMESTAMP; 
SELECT DATEDIFF(today,birthdate)/365 AS ageInYears
FROM PERSON;
END $$
DELIMITER ;

call determineAge('June 25, 1981');

Answer 1

This works. No need to declare “today” – just use a NOW() function in your query.

Also, no need to select FROM anything… you’re just querying a single value.

Your date was formatted wrong (MySQL requires 'YYYY-MM-DD', and you want to floor the difference to get a whole number of years.

DELIMITER $$
CREATE PROCEDURE determineAge(IN birthDate DATE)
BEGIN
    SELECT FLOOR(DATEDIFF(NOW(), DATE(birthdate))/365);
END $$
DELIMITER ;

CALL determineAge('1981-06-25');

Finally, you could theoretically return the year value as an OUT param if you wanted to, though a query result is just fine.

DELIMITER $$
CREATE PROCEDURE determineAge(IN birthDate DATE, OUT age INT)
BEGIN
    SELECT FLOOR(DATEDIFF(NOW(), DATE(birthdate))/365) INTO age;
END $$
DELIMITER ;

There you go!