Question

我需要从一栏中一栏中找到最大值,而另一栏的数值相当于某种数值。但是,由于有人问我是否使用过,我不断收到显示和错误的信息。我的询问如下:

SELECT MAX(message_id) AS top_message HAVING(child_id) =  ".$message_id[$i]."

任何建议?

Answer 1

页: 1

SELECT MAX(message_id) AS top_message FROM tablename WHERE child_id =  ".$message_id[$i]."

Answer 2

页: 1 WHERE und HAVING 条款:

SELECT MAX(message_id) AS top_message 
FROM tablename 
WHERE child_id =  ".$message_id[$i]."

仅使用<代码>HAVING 条款,如果您有合计的混合物。

Answer 3

You need a from clause and a where clause. The having clause is used for group filters. You don t have a group by clause, so there is no reason to write a having clause. If the table where you want to select from is called MyTable , then your query is as follows:

SELECT MAX(message_id) AS top_message
FROM MyTable
WHERE child_id =  ".$message_id[$i]."

值得注意的是,不需要围绕儿童补贴的瘫痪。请阅读和MySQL辅导,了解更多情况,你的生活将更加容易。

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