I would like the ability to expose and edit SQL for hosted feature layer views. This would allow much greater customization and control over the views. An example where this can be used is when you want to filter the layer based on something dynamic. For example, if you have a feature layer that has CreationDate and EditDate attributes and you want to filter for records where the EditDate is within 14 days of the CreationDate:
select * from [FeatureLayer] where EditDate <= DATEADD(day,14,convert(date,CreationDate))
Another example is where you want to have a dynamically generated attribute on the view that is perhaps a concatenation of two attributes in the feature layer:
Select [FeatureLayer].*, concat([Status] + '-' + [Priority]) as [Defect_priority]
Or even Case statements:
case when [EditDate] > DATEADD(day,14,convert(date,CreationDate)) then 'Overdue'
when [EditDate] <= DATEADD(day,14,convert(date,CreationDate)) then 'OnTime'
when [EditDate] is null then 'Open'
Else '' end as [CurrentStatus]
All of this can be done in an RDBMS such as SQL Server, however it could be useful to have this functionality for organizations that are using AGOL only.