I have created a Data Extension (account) which contains an account_id and various boolean fields and email address, I want to create a field which stores the last opened date from _Opened table via
MAX(o.EventDate) as last_opened_date
from account a
left join _Open o
on o.SubscriberKey = a.SubscriberKey
GROUP BY a.SubscriberKey
I'm getting this error however
An error occurred while checking the query syntax. Errors: Column 'C10959787.account.email_address' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause.
Can someone tell me what I'm doing wrong?