更新数据库中的最大值php mysql的列 [英] Update column in database where max value php mysql

问题描述

我在这里遇到问题.即时更新名称，其中B具有最大的价值.

I got problem here. im updating name where B has the biggest value.

所以结果是

B  | name
---|------
 1 | 
 2 | 
 3 | YES

但是当B列更改值时，问题是行名称为3的列名仍然有一个值.

but when column B changes value the problem is column name with row value 3 still has a value.

B  | name
---|------
 1 | 
 4 | YES
 3 | YES  

结果应该是.

B  | name
---|------
 1 | 
 4 | YES
 3 |   

如果

B  | name
---|------
 0 | 
 0 | 
 0 |  

然后

B  | name
---|------
 0 | 
 0 | 
 0 |  

如果

B  | name
---|------
 4 | 
 4 | 
 2 | 

然后

B  | name
---|------
 4 | YES
 4 | YES
 2 |   

这就是我想要的.

仅使用此简单代码.

$sql3 = "UPDATE products SET name='YES' ORDER BY B DESC";

推荐答案

我想您要更新表中B列为最高值的行?您肯定需要"WHERE"子句，但您还需要知道该列中的最高值.为什么不先查询数据库以从B列检索最大值?

I think you want to update the row in the the table where column B is the highest value? You definitely need a "WHERE" clause, but you also need to know the highest value in that column. Why don't you query the database first to retrieve the highest value from column B?

$maxvalue = "SELECT `B` FROM products ORDER BY `B` DESC LIMIT 1"

然后将B列等于此值插入数据库中吗?

and then insert into the database WHERE the column B equals this value?

"UPDATE products SET name='YES' WHERE B = $maxvalue"

这不是完整的代码，只是概念上的.我将清理并编辑此答案...

This is not complete code, just conceptual. I will clean it up and edit this answer...

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