What are some common mistakes to avoid when using "ORDER BY" in PHP?

One common mistake to avoid when using "ORDER BY" in PHP is forgetting to include the column name in the query. This can lead to unexpected results or errors. To solve this issue, always make sure to specify the column name after the "ORDER BY" keyword in your SQL query. Example:

// Incorrect way - missing column name
$query = "SELECT * FROM users ORDER BY"; 

// Correct way - specify column name
$query = "SELECT * FROM users ORDER BY user_id";