Question

How do I get count of distinct rows with duplicate email IDs in SQL?

ID   NAME   EMAIL 
1    John   [e-mail] 
2    Sam    [e-mail] 
4    Bob    [e-mail] 
5    Tom    [e-mail] 
6    Rob    [e-mail]
7    Tic    [e-mail]
8    Dad    [e-mail]

The query should return 2.
as [e-mail] and [e-mail] are duplicates

SELECT 
 COUNT(*)  
FROM Users
GROUP BY EMail 
HAVING ( COUNT(EMAIL) > 1 )    

This query is returning some wierd results.
Thanks

Answer 1

Count of rows:

select sum(cnt)
from (select count(*) as cnt
    from Users
    group by email
    having count(*) > 1) T

Count of emails:

select count(*)
from (select count(*) as cnt
    from Users
    group by email
    having count(*) > 1) T

Both at once:

select count(*) as COUNT_EMAIL sum(cnt) as COUNT_ROWS
from (select count(*) as cnt
    from Users
    group by email
    having count(*) > 1) T

Above should work on SQL Server and Oracle.