Database users

Until version 11.70.xC2, Informix® database users must be created at the operating system level and be members of the 'informix' group. Starting with 11.70.xC2, Informix supports database-only users with the CREATE USER instruction, as most other db servers. Any database user must have sufficient privileges to connect and use resources of the database; user rights are defined with the GRANT command.

MySQL users must be registered in the database. They are created with the GRANT SQL instruction:
$ mysql -u root -pmanager --host orion test
mysql>  GRANT ALL PRIVILEGES ON * TO mike IDENTIFIED BY 'pswd';

Solution

According to the application logic (is it a multiuser application?), you have to create one or several MySQL users.