Why is the use of "alter" causing issues in the code?

The issue with using "alter" in the code is that it is a reserved keyword in SQL, which can lead to syntax errors or unexpected behavior. To solve this issue, you can either rename the variable to something that is not a reserved keyword or wrap the keyword in backticks (`) to escape it.

// Rename the variable to something that is not a reserved keyword
$alterVariable = "value";

// Or wrap the keyword in backticks to escape it
$query = "ALTER TABLE `table_name` ADD COLUMN `alter` VARCHAR(255)";