Email duplicates

how to find duplicate emails

SELECT        COUNT(Email) AS numDups, Email
FROM            dbo.Person
GROUP BY Email
HAVING        (COUNT(Email) > 1)
  

or duplicate company / phone etc

SELECT        COUNT(Company) AS numDups, Company
FROM            dbo.Person
GROUP BY Company
HAVING        (COUNT(Company) > 1)

or num times logged in 

SELECT        TOP (100) PERCENT COUNT(LastIpAddress) AS numTimesLoggedIn, LastIpAddress, MAX(LastLoginDate) AS LastLoginDate
FROM            dbo.Person
GROUP BY LastIpAddress
HAVING        (COUNT(LastIpAddress) > 1)
ORDER BY LastLoginDate DESC