I am having issues with setting up mysql config file for relative paths, therefore I editted the my.ini file.
Static paths work perfectly: tmpdir = "C:/xampp/tmp" datadir = "C:/xampp/mysql/data"
Relative paths aren't (root folder should be xampp I guess): tmpdir = "tmp" datadir = "data"
I cannot imagine that there is no way to achieve relative paths to the project.
You can do that but always start your mysqld server manually (not automatically by windows service) to make sure the current directory.
From the manual: https://dev.mysql.com/doc/refman/5.6/en/server-system-variables.html