How to Select Every Row Where Column Value is NOT Distinct
SqlSql ServerSql Server-2008Sql Problem Overview
I need to run a select statement that returns all rows where the value of a column is not distinct (e.g. EmailAddress).
For example, if the table looks like below:
CustomerName EmailAddress
Aaron aaron@gmail.com
Christy aaron@gmail.com
Jason jason@gmail.com
Eric eric@gmail.com
John aaron@gmail.com
I need the query to return:
Aaron aaron@gmail.com
Christy aaron@gmail.com
John aaron@gmail.com
I have read many posts and tried different queries to no avail. The query that I believe should work is below. Can someone suggest an alternative or tell me what may be wrong with my query?
select EmailAddress, CustomerName from Customers
group by EmailAddress, CustomerName
having COUNT(distinct(EmailAddress)) > 1
Sql Solutions
Solution 1 - Sql
This is significantly faster than the EXISTS way:
SELECT [EmailAddress], [CustomerName] FROM [Customers] WHERE [EmailAddress] IN
(SELECT [EmailAddress] FROM [Customers] GROUP BY [EmailAddress] HAVING COUNT(*) > 1)
Solution 2 - Sql
The thing that is incorrect with your query is that you are grouping by email and name, that forms a group of each unique set of email and name combined together and hence
aaron and aaron@gmail.com
christy and aaron@gmail.com
john and aaron@gmail.com
are treated as 3 different groups rather all belonging to 1 single group.
Please use the query as given below :
select emailaddress,customername from customers where emailaddress in
(select emailaddress from customers group by emailaddress having count(*) > 1)
Solution 3 - Sql
select CustomerName,count(1) from Customers group by CustomerName having count(1) > 1
Solution 4 - Sql
How about
SELECT EmailAddress, CustomerName FROM Customers a
WHERE Exists ( SELECT emailAddress FROM customers c WHERE a.customerName != c.customerName AND a.EmailAddress = c.EmailAddress)
Solution 5 - Sql
Just for fun, here's another way:
;with counts as (
select CustomerName, EmailAddress,
count(*) over (partition by EmailAddress) as num
from Customers
)
select CustomerName, EmailAddress
from counts
where num > 1
Solution 6 - Sql
Rather than using sub queries in where condition which will increase the query time where records are huge.
I would suggest to use Inner Join as a better option to this problem.
Considering the same table this could give the result
SELECT EmailAddress, CustomerName FROM Customers as a
Inner Join Customers as b on a.CustomerName <> b.CustomerName and a.EmailAddress = b.EmailAddress
For still better results I would suggest you to use CustomerID or any unique field of your table. Duplication of CustomerName is possible.
Solution 7 - Sql
SELECT Title, Id
FROM dbo.TblNews
WHERE (Title IN
(SELECT Title
FROM dbo.TblNews AS TblNews_1
GROUP BY Title
HAVING (COUNT(*) > 1)))
ORDER BY Title
- sort in title