避免NULL计数mysql

Question

我有这个选择：

select 'fv' prefix, c.user, MAX(f.data) as data, c.user, count(c.user) as logs
from favorites f inner join
     cadastro c
     ON f.user = c.id
where f.fv = '1' and c.user <> f.user and f.data > now()

如果我没有显示结果，mysql会显示：

prefix - user - data - user - logs
fv NULL NULL NULL 0

我不想在没有结果时显示。怎么了？伯爵（c.user）？我怎样才能避免数到0？

Answer 1

没有select 'fv' as prefix, c.user, MAX(f.data) as data, c.user, count(c.user) as logs from favorites f inner join cadastro c ON f.user = c.id where f.fv = '1' and c.user <> f.user and f.data > now() group by f.fv; 的聚合查询总是返回一行。一种简单的方法是添加聚合：

function SublistMouseenter(myAnchorsID) {
    if (document.getElementById(myAnchorsID).className == "HeaderCategoryLink") {
        document.getElementById(myAnchorsID).className = "header-menu-sublist-hover";
    } else {
        document.getElementById(myAnchorsID).className = "HeaderCategoryLink";
    }
}

如果没有匹配项，则不会返回任何行。