SELECT
CONVERT(varchar(8), [ConnectionDate], 112) AS conDate,
COUNT([ID]) AS 'Antal anslutningar'
FROM [vRDDotaccess].[dbo].[vRDHistory]
GROUP BY 'conDate'
ORDER BY 'conDate'


Msg 164, Level 15, State 1, Line 1
Each GROUP BY expression must contain at least one column that is not an outer reference.