mysql中DATE_DIFF出错

I keep getting an error trying to implement DATE_DIFF in mySQL.

I'm trying to get the number of days between "hm_date" and the present day, and have the number appear in a different field called "total_days".

Doing this on servier-side, my code is getting an error: #1305 - FUNCTION naturan8_41q.DATE_DIFF does not exist

SELECT * FROM reg_add WHERE DATE_DIFF(hm_date,total_days)

You are using DATE_DIFF, thats the error. DATEDIFF is the correct function name.

Corrected Query: SELECT DATEDIFF(curdate(),hm_date) as total_days FROM reg_add.

DATEDIFF is the correct name, without spaces (indeed, it is confusing and inconsistent with DATE_ADD and DATE_FORMAT)

SELECT DATEDIFF(curdate(), hm_date) as total_days FROM reg_add