sql_mode=only_full_group_by

[Bernie van't Hof]

SELECT DISTINCT
`A/C#` AS `A/C#`,
`MyRef` AS `MyRef`,
DATEDIFF('2017-06-30', `Date`) AS `Days`,
`Dr` - `Cr` AS `Balance`
FROM
`BERNIE`.`answer`
GROUP BY
`A/C#`,
`MyRef`
ORDER BY
BINARY `A/C#`,
BINARY `MyRef`,
`Days`,
`Balance`

ERROR: Expression #3 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'bernie.answer.Date' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

Can make the error go away by including Date, Dr, and Cr in the GROUP BY.

Adding the aliases of the calculated fields (Days & Balance) to the GROUP BY also runs gets rid of the error. Now I'm more confused.