a question about DATE_ADD

Question

I want to add 1 month and 3 months, should I do like that:

UPDATE `set` SET expire = DATE_ADD(`expire`, INTERVAL 1 MONTH) WHERE ID='$lid'

UPDATE `set` SET expire = DATE_ADD(`expire`, INTERVAL 3 MONTHS) WHERE ID='$lid'

is that right ?

3 MONTH or 3 MONTHS ?

Answer 1

No, it's always MONTH - singular.

UPDATE `set` SET expire = DATE_ADD(`expire`, INTERVAL 3 MONTH) WHERE ID='$lid'

Answer 2

Here is a safe way for you to try both syntaxes and see for yourself:

SELECT expire,DATE_ADD(expire,INTERVAL 3 MONTH) FROM set LIMIT 5;
SELECT expire,DATE_ADD(expire,INTERVAL 3 MONTHS) FROM set LIMIT 5;