PHP Mysqli查询更新无法使用变量

Question

I have this query:

$date = "january";
mysqli_query($connection->dbconn, "UPDATE monthly_visitors SET '$date' = 0");

But for some reason it does not work. The variable doesn't seem to work inside the query. Ideas why this is happening?

Answer 1

It seems like you're trying to set the value in a column called "january" to zero for all rows. Is that really what you want to do? If so then try to remove the quotes around "$date". It shouldn't be quoted because it's a column name.

Also, note that if $date would come from a user then this code snippet would be susceptible for SQL injections. Never use user input directly in a query. Verify it / escape it / use parameters instead.