Incompatible GROUP BY Clause Error in MySQL: Solutions

you might have encountered the error message "Incompatible GROUP BY Clause". This error can be caused by the sql_mode=only_full_group_by default setting.

sql_mode=only_full_group_by setting, which is enabled by default in newer versions of MySQL.

This setting requires all columns in the SELECT statement to be included in the GROUP BY clause, which can cause issues if you're working with complex queries.

In this article, we'll explore the causes of the "Incompatible GROUP BY Clause" error and provide solutions for how to fix it. We'll cover both short-term and long-term solutions, including modifying the MySQL configuration, adjusting the query, or rewriting the query entirely. By the end of this article, you'll have a better understanding of how to handle this error and avoid it in the future.

Short-term solutions include disabling the only_full_group_by mode for the current session or for specific queries using the SQL command SET. However, these solutions are temporary and may not be suitable for long-term use.

To disable the only_full_group_by mode for the current session, you can use the SQL command SET. Follow these steps:

1. Open your MySQL client or phpMyAdmin and connect to your MySQL server.

2. Run the following SQL command to disable the only_full_group_by mode:


This command removes the ONLY_FULL_GROUP_BY flag from the current SQL mode and sets it to the modified SQL mode.

3. Run your query again to see if the error has been resolved

Note that this solution is temporary and only disables the only_full_group_by mode for the current session. If you need a more permanent solution, consider modifying the MySQL configuration file or rewriting your query to avoid the error.

To disable the only_full_group_by mode permanently, you need to modify the MySQL configuration file. Follow these steps:

1. Open your MySQL configuration file. This file is usually named my.cnf or my.ini, depending on your operating system.

2. Look for the sql_mode setting. This setting may be in the [mysqld] section or the [mysql] section, depending on your MySQL version.

3. Modify the sql_mode setting to remove the ONLY_FULL_GROUP_BY flag. For example, if the current value of sql_mode is:


Change it to:


Note that we've removed the ONLY_FULL_GROUP_BY flag from the value

4. Save the configuration file and restart your MySQL server for the changes to take effect.

After restarting the server, the only_full_group_by mode will be disabled permanently. However, keep in mind that modifying the MySQL configuration file can have unintended consequences, so make sure to test your applications thoroughly after making any changes.