Question

我有查询

SELECT helpc.cid, COUNT(help.cid) AS children_count FROM air_help_category AS helpc LEFT JOIN air_help AS help ON helpc.cid = help.cid GROUP BY cid WHERE hildren_count > 0

但我得到

＃1064 - 您的SQL语法出错;检查与您的MySQL服务器版本对应的手册，以便在'WHERE children_count＆gt;附近使用正确的语法; 0限制0,30'在第1行

检查了相应的错误代码，但仍然无法解决此问题。

我所要做的就是找到那些至少有一个孩子的ids。

Answer 1

将'group'放在'group by'之前

Answer 2

SELECT helpc.cid, COUNT(help.cid) AS children_count
FROM air_help_category AS helpc LEFT JOIN air_help AS help
ON (helpc.cid = help.cid) WHERE children_count &lt; 0 GROUP BY cid

Answer 3

首先，WHERE子句应该在GROUP BY之前。此外，您不能使用WHERE的汇总字段值 - 请改用HAVING，如下所示：

SELECT helpc.cid, COUNT(help.cid) AS children_count 
FROM air_help_category AS helpc LEFT JOIN air_help AS help ON helpc.cid = help.cid 
GROUP BY cid 
HAVING COUNT(help.cid) > 0

尝试限制count（）不为0的结果时出现mysql错误＃1064

3 个答案: