MySQL按月交叉表查询，返回默认值1'；s

如果当月没有值，当我告诉查询默认为“0”时，为什么查询返回“1”

以下是我的结果：

---

别介意我上次（删除的）评论。。显示表结构和示例数据将其放在sqlfiddle.com或db fiddle.com上。。此外，你知道你是误用MySQL的功能组？通过选择不在GROUP By子句中的列。。这就是为什么您还应该将预期结果作为格式化文本包含的原因。

count（distinct 0）

统计不同值的数量。有1个不同的值（即值0），如果select不返回任何行，则没有。很难弄清楚您想要的是什么（可能完全删除

或者
-部分？），因此，正如Raymond所说，提供一些示例数据和预期结果。谢谢各位。。删除ELSE 0成功了！
SELECT  td_type,

COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%01') THEN (ttNum)    ELSE    0   END ) AS 'Jan',
COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%02') THEN (ttNum)    ELSE    0   END ) AS 'Feb',
COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%03') THEN (ttNum)    ELSE    0   END ) AS 'Mar',
COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%04') THEN (ttNum)    ELSE    0   END ) AS 'Apr',
COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%05') THEN (ttNum)    ELSE    0   END ) AS 'May',
COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%06') THEN (ttNum)    ELSE    0   END ) AS 'Jun',
COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%07') THEN (ttNum)    ELSE    0   END ) AS 'Jul',
COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%08') THEN (ttNum)    ELSE    0   END ) AS 'Aug',
COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%09') THEN (ttNum)    ELSE    0   END ) AS 'Sep',
COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%10') THEN (ttNum)    ELSE    0   END ) AS 'Oct',
COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%11') THEN (ttNum)    ELSE    0   END ) AS 'Nov',
COUNT(DISTINCT CASE WHEN DATE_FORMAT(ttDate,'%Y-%m') = DATE_FORMAT(NOW(), '%Y-%12') THEN (ttNum)    ELSE    0   END ) AS 'Dec',
            COUNT(ttNum) AS Total

FROM      v_closed_tickets
WHERE (DATE_FORMAT(ttDate, '%Y%') = DATE_FORMAT(NOW(), '%Y%')) AND ttCategory IN ('TT') 

GROUP BY ccOption