Solution 1: Remove ONLY_FULL_GROUP_BY from mysql console
mysql > SET GLOBAL sql_mode=(SELECT REPLACE(@@sql_mode,'ONLY_FULL_GROUP_BY',''));
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Solution 2: Remove ONLY_FULL_GROUP_BY from phpmyadmin
Open phpmyadmin & select localhost
Click on menu Variables & scroll down for sql mode
Click on edit button to change the values & remove ONLY_FULL_GROUP_BY & click on save.