Cause - The active version of Oracle Grid Infrastructure detected on the system (12.1.0.2.0), is lower than the version of Oracle Real Application Database software that you were attempting to install(12.2.0.1.0).This is not supported.  Action - If Oracle Grid Infrastructure is of older version, only Oracle Single Instance Database software can be installed. If you want to install Oracle Real Application Database software,you should upgrade Oracle Grid Infrastructure to same or higher version first.
根据以上信息，GI版本不能低于DATABASE的版本，换句话说，高版本的GI可以安装低版本的database