Question

See the following SQL statement:

SELECT datediff("d", MAX(invoice.date), Now) As Date_Diff
      , MAX(invoice.date) AS max_invoice_date
      , customer.number AS customer_number
FROM invoice 
    INNER JOIN customer 
        ON invoice.customer_number = customer.number
GROUP BY customer.number 

If the the following was added:

HAVING datediff("d", MAX(invoice.date), Now) > 365

would this simply exclude rows with Date_Diff <= 365?

What should be the effect of the HAVING clause here?

EDIT: I am not experiencing what the answers here are saying. A copy of the mdb is at http://hotfile.com/dl/40641614/2353dfc/test.mdb.html (no macros or viruses). VISDATA.EXE is being used to execute the queries.

EDIT2: I think the problem might be VISDATA, because I am experiencing different results via DAO.

Answer 1

As already pointed out, yes, that is the effect. For completeness, ‘HAVING’ is like ‘WHERE’, but for the already aggregated (grouped) values (such as, MAX in this case, or SUM, or COUNT, or any of the other aggregate functions).