Automatically warn against the use of mysql_* functions on Stack Overflow
I've seen several questions now where the code includes deprecated functions.
I'll use Mysql_ function for this example... The user posts a question with deprecated mysql_, and immediately several people respond with "don't use that, use PDO or Mysqli"...
Would it be useful to have Stackoverflow to search keywords and give a notice to the user that certain terms are no longer valid to save trouble? The notice would of course include an comprehensive explanation, along with links to better alternatives... I think this would save a lot of hassle.
Here are two recent examples I've seen: