Error related to only_full_group_by when executing a query in MySql

If you don't want to make any changes in your current query then follow the below steps -

1. vagrant ssh into your box
2. Type: sudo vim /etc/mysql/my.cnf
3. Scroll to the bottom of file and type A to enter insert mode

4. Copy and paste

   [mysqld]
   sql_mode = STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION
   

5. Type esc to exit input mode

6. Type :wq to save and close vim.
7. Type sudo service mysql restart to restart MySQL.

You can try to disable the only_full_group_by setting by executing the following:

mysql> set global sql_mode='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';
mysql> set session sql_mode='STRICT_TRANS_TABLES,NO_ZERO_IN_DATE,NO_ZERO_DATE,ERROR_FOR_DIVISION_BY_ZERO,NO_AUTO_CREATE_USER,NO_ENGINE_SUBSTITUTION';

MySQL 8 does not accept NO_AUTO_CREATE_USER so that needs to be removed.

you can turn off the warning message as explained in the other answers or you can understand what's happening and fix it.

As of MySQL 5.7.5, the default SQL mode includes ONLY_FULL_GROUP_BY which means when you are grouping rows and then selecting something out of that groups, you need to explicitly say which row should that selection be made from.

Mysql needs to know which row in the group you're looking for, which gives you two options

• You can also add the column you want to the group statement group by rect.color, rect.value which can be what you want in some cases otherwise would return duplicate results with the same color which you may not want
• you could also use aggregate functions of mysql to indicate which row you are looking for inside the groups like AVG() MIN() MAX() complete list
• AND finally you can use ANY_VALUE() if you are sure that all the results inside the group are the same. doc

I would just add group_id to the GROUP BY.

When SELECTing a column that is not part of the GROUP BY there could be multiple values for that column within the groups, but there will only be space for a single value in the results. So, the database usually needs to be told exactly how to make those multiple values into one value. Commonly, this is done with an aggregate function like COUNT(), SUM(), MAX() etc... I say usually because most other popular database systems insist on this. However, in MySQL prior to version 5.7 the default behaviour has been more forgiving because it will not complain and then arbitrarily choose any value! It also has an ANY_VALUE() function that could be used as another solution to this question if you really needed the same behaviour as before. This flexibility comes at a cost because it is non-deterministic, so I would not recommend it unless you have a very good reason for needing it. MySQL are now turning on the only_full_group_by setting by default for good reasons, so it's best to get used to it and make your queries comply with it.

So why my simple answer above? I've made a couple of assumptions:

1) the group_id is unique. Seems reasonable, it is an 'ID' after all.

2) the group_name is also unique. This may not be such a reasonable assumption. If this is not the case and you have some duplicate group_names and you then follow my advice to add group_id to the GROUP BY, you may find that you now get more results than before because the groups with the same name will now have separate rows in the results. To me, this would be better than having these duplicate groups hidden because the database has quietly selected a value arbitrarily!

It's also good practice to qualify all the columns with their table name or alias when there's more than one table involved...

SELECT 
  g.group_id AS 'value', 
  g.group_name AS 'text' 
FROM mod_users_groups g
LEFT JOIN mod_users_data d ON g.group_id = d.group_id 
WHERE g.active = 1 
  AND g.department_id = 1 
  AND g.manage_work_orders = 1 
  AND g.group_name != 'root' 
  AND g.group_name != 'superuser' 
GROUP BY 
  g.group_name, 
  g.group_id 
HAVING COUNT(d.user_id) > 0 
ORDER BY g.group_name