Had this same issue in Centos 6 and Centos 7
just to clarify how to do that
Login as root and vi /etc/my.cnf
Unhash the line that looks like
# Optionally change the SQL mode.
#sql_mode=ONLY_FULL_GROUP_BY,STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
and change it to
sql_mode=STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
so you are Enabling that line and removing the "ONLY_FULL_GROUP_BY," part
Regards Garry, Outback Central Australia