SQL:HAVING子句

Question

请参阅以下SQL语句:

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 

如果添加以下内容:

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

这会简单地排除Date_Diff <= 365的行吗？

这里的HAVING条款会有什么影响？

编辑:我没有体验到这里的答案.mdb的副本位于http://hotfile.com/dl/40641614/2353dfc/test.mdb.html(无宏或病毒).VISDATA.EXE用于执行查询.

EDIT2:我认为问题可能是VISDATA,因为我通过DAO遇到了不同的结果.

Answer 1

正如已经指出的那样,是的,就是效果.为了完整性,'HAVING'类似于'WHERE',但是对于已经聚合的(分组的)值(例如,在这种情况下为MAX,或SUM,或COUNT,或任何其他聚合函数).