Q&A for professional robotic engineers, hobbyists, researchers and students
SELECT 'MIN', MIN(DATEDIFF(DAY, CreationDate, GETDATE())) as Acct_Age_Days FROM Users UNION SELECT 'MAX', MAX(DATEDIFF(DAY, CreationDate, GETDATE())) FROM Users UNION SELECT 'MEAN', AVG(CAST(DATEDIFF(DAY, CreationDate, GETDATE()) AS BIGINT)) FROM Users