Sometimes there are problems with file encoding. If you get question marks instead of some special characters, then you probably need to change encoding(default is utf-8). This is project based so its bad to have different kinds of encodings in one project.
How to change the encoding:
Open projects properties.
The first tab contains Encoding dropdown menu.
I have some projects with ISO-8859-1 and UTF-8.
If you dont use utf-8 in sql database then do utf8_decode before inserting or updating your data.