PHP中的MySQL查询使用变量作为列的名称

I'm trying to do a MySQLi query in PHP but the name of one of the columns is stored in a variable ($year):

我正在尝试在PHP中执行MySQLi查询,但其中一列的名称存储在变量($ year)中:

$result = mysqli_query($con,"SELECT table4.Country, AVG('.$year.')  AS 'Total' 
                             FROM table4 
                             WHERE table4.Region IN ($region)");

This query returns 0 as average value. I think that the problem could be that $year is a number and I don't know if a column can have an integer as name.

此查询返回0作为平均值。我认为问题可能是$ year是一个数字,我不知道列是否可以有一个整数作为名称。

How can I solve this problem?

我怎么解决这个问题?

Thanks in advance!

提前致谢!

1 个解决方案

#1

Your code is not proper. As per your code MySQL will try to find the AVG('.$year.') which is not a valid expression. This needs to be changed.

你的代码不合适。根据你的代码,MySQL会尝试找到AVG('。$ year。'),这不是一个有效的表达式。这需要改变。

So, assuming the $year contains field name which is non-integer, Try this below code:

因此,假设$ year包含非整数字段名称,请尝试以下代码:

$result = mysqli_query($con,"SELECT table4.Country, AVG(`".$year."`)  AS 'Total' FROM table4 WHERE table4.Region IN ($region)");

Hope this helps.

希望这可以帮助。

#1