When writing PLSQL in the Oracle database, you define parameters to a function/procedure like this:
Instead of writing it like that, consider using a table.column definition as type for your parameter! This way, if you change your table, you will not also have to change your code!
Now, if you for some reason change the ID column in the SIGNUP table to be something other than INTEGER, you can leave the code as is! Much more DRY!