How to calculate difference between two dates in months in MySQL - mysql

Question

I have two columns in a MySQL table:
DateOfService (datetime)
BirthDate (date)
I want to run a MySQL query that will provide date difference between these two fields in months.
How can I do this in a MySQL select query?
Thanks.

Answer 1

Have a look at the TIMESTAMPDIFF() function in MySQL.
What this allows you to do is pass in two TIMESTAMP or DATETIME values (or even DATE as MySQL will auto-convert) as well as the unit of time you want to base your difference on.
You can specify MONTH as the unit in the first parameter:
SELECT TIMESTAMPDIFF(MONTH, '2012-05-05', '2012-06-04')
-- 0
SELECT TIMESTAMPDIFF(MONTH, '2012-05-05', '2012-06-05')
-- 1
SELECT TIMESTAMPDIFF(MONTH, '2012-05-05', '2012-06-15')
-- 1
SELECT TIMESTAMPDIFF(MONTH, '2012-05-05', '2012-12-16')
-- 7
It basically gets the number of months elapsed from the first date in the parameter list. This solution accounts for the varying amount of days in each month (28,30,31) as well as leap years.
If you want decimal precision in the number of months elapsed, it's a little more complicated, but here is how you can do it:
SELECT
TIMESTAMPDIFF(MONTH, startdate, enddate) +
DATEDIFF(
enddate,
startdate + INTERVAL
TIMESTAMPDIFF(MONTH, startdate, enddate)
MONTH
) /
DATEDIFF(
startdate + INTERVAL
TIMESTAMPDIFF(MONTH, startdate, enddate) + 1
MONTH,
startdate + INTERVAL
TIMESTAMPDIFF(MONTH, startdate, enddate)
MONTH
)
Where startdate and enddate are your date parameters, whether it be from two date columns in a table or as input parameters from a script:
Examples:
With startdate = '2012-05-05' AND enddate = '2012-05-27':
-- Outputs: 0.7097
With startdate = '2012-05-05' AND enddate = '2012-06-13':
-- Outputs: 1.2667
With startdate = '2012-02-27' AND enddate = '2012-06-02':
-- Outputs: 3.1935

Answer 2

This could work:
SELECT 12 * (YEAR(DateOfService)
- YEAR(BirthDate))
+ (MONTH(DateOfService)
- MONTH(BirthDate)) AS months
FROM table

Answer 3

Try this:
SELECT DATEDIFF(DateOfService, BirthDate) / 30 as months FROM ...

Answer 4

TRY with
PERIOD_DIFF(P1,P2)
Returns the number of months between periods P1 and P2. P1 and P2 should be in the format YYMM or YYYYMM. Note that the period arguments P1 and P2 are not date values.
mysql> SELECT PERIOD_DIFF(200802,200703);
-> 11

Answer 5

TIMESTAMPDIFF(MONTH, Start_date, End_date)
Example:
SELECT TIMESTAMPDIFF(MONTH, BirthDate, DateOfService) AS Months FROM Table

Answer 6

Based on a summary of all answers and a Google search, I think there are four almost similar ways to write it:
1)
TIMESTAMPDIFF(MONTH, Start_date, End_date) AS Period
E.g.
TIMESTAMPDIFF(MONTH, MIN(r.rental_date), MAX(r.rental_date)) AS Period
2)
PERIOD_DIFF(date_format(now(), '%Y%m'), date_format(time, '%Y%m')) as months
Or
PERIOD_DIFF(date_format(End_date(), '%Y%m'), date_format(Start_date, '%Y%m')) as months
E.g.
PERIOD_DIFF(date_format(MAX(r.rental_date), '%Y%m'), date_format(MIN(r.rental_date), '%Y%m')) as months
3)
PERIOD_DIFF(EXTRACT(YEAR_MONTH FROM NOW()), EXTRACT(YEAR_MONTH FROM time)) AS months
OR
PERIOD_DIFF(EXTRACT(YEAR_MONTH FROM End_date()), EXTRACT(YEAR_MONTH FROM Start_date)) AS months
E.g.
PERIOD_DIFF(EXTRACT(YEAR_MONTH FROM MAX(r.rental_date)), EXTRACT(YEAR_MONTH FROM MIN(r.rental_date))) as Months
4)
PERIOD_DIFF(concat(year(d1),if(month(d1)<10,'0',''),month(d1)), concat(year(d2),if(month(d2)<10,'0',''),month(d2))) as Months**
E.g.
PERIOD_DIFF(
concat(year(MAX(r.rental_date)),if(month(MAX(r.rental_date))<10,'0',''),month(MAX(r.rental_date))),
concat(year(MIN(r.rental_date)),if(month(MIN(r.rental_date))<10,'0',''),month(MIN(r.rental_date)))
) as Months

Answer 7

The 'right' answer depends on exactly what you need. I like to round to the closest whole number.
Consider these examples:
1st January -> 31st January: It's 0 whole months, and almost 1 month long.
1st January -> 1st February? It's 1 whole month, and exactly 1 month long.
To get the number of whole months, use:
SELECT TIMESTAMPDIFF(MONTH, '2018-01-01', '2018-01-31'); => 0
SELECT TIMESTAMPDIFF(MONTH, '2018-01-01', '2018-02-01'); => 1
To get a rounded duration in months, you could use:
SELECT ROUND(TIMESTAMPDIFF(DAY, '2018-01-01', '2018-01-31')*12/365.24); => 1
SELECT ROUND(TIMESTAMPDIFF(DAY, '2018-01-01', '2018-01-31')*12/365.24); => 1
This is accurate to +/- 5 days and for ranges over 1000 years. Zane's answer is obviously more accurate, but it's too verbose for my liking.