SQL - check for duplicate names/nicknames - sql

Question

I have a query that gives me duplicate names in my table. But, I need to add the checking of nicknames. I've tried many variations but am still stumped. The following query takes oave 12 minutes to run so I canceled it.
WITH TEAM2 as
(
SELECT ID, LastName, FirstName, Name,
ROW_NUMBER() OVER (PARTITION BY LastName, FirstName order by LastName, FirstName,ID DESC) RN
FROM dbo.vw_Users_Details
WHERE Lastname <> ''
AND Firstname <> ''
AND Not_Dupe_Flag <> 1
)
SELECT a.ID, a.LastName, a.FirstName
FROM TEAM2 a
where exists (select 1
from TEAM2 b
where (b.FirstName = a.FirstName
and b.LastName = a.LastName
and b.RN > 1)
OR
(b.LastName = a.LastName
AND EXISTS (SELECT 1 FROM pdNicknames AS c WHERE c.NAME = a.firstname AND c.variation = b.firstname)
and b.RN > 1)
)
order by a.LastName, a.FirstName, a.id

Answer 1

You can use the having clause.
For example:
select b.Branches_ShortName
from kplus..Folders f
inner join kplus..Portfolios p on p.Portfolios_Id = f.Portfolios_Id
inner join kplus..Branches b on b.Branches_Id = p.Branches_Id
group by Branches_ShortName
having count(Branches_ShortName) > 1
This will provide only the Branches that have more than 1 Folder :)

Answer 2

Okay, you're attempting to find all users who share the same name/nickname.
I believe the following should work;
SELECT a.ID, a.LastName, a.FirstName
FROM dbo.vw_Users_Details as a
WHERE a.LastName <> ''
AND a.FirstName <> ''
AND EXISTS (SELECT '1'
FROM dbo.vw_Users_Details as b
LEFT JOIN pdNicknames as c
ON (c.name = b.FirstName
AND c.variation = a.FirstName)
OR (c.name = a.FirstName
AND c.variation = b.FirstName)
WHERE b.ID <> a.ID
AND b.LastName = a.LastName
AND (b.FirstName = a.FirstName
OR (c.name IS NOT NULL OR c.variation IS NOT NULL)
)
)
I make no garuantees about the execution performance of this statement, as you haven't provided enough information for us to know. However, it's likely to be better, given you won't need the OLAP; I do recommend indicies on the various names and variation, of course. I left off Not_Dupe_Flag because I'm a little confused by it's use (because you seem to be using '1' as 'false', which is opposite to how most comparisons are setup); at minimum, never include 'Not' as part of a boolean variable name - it makes reasoning about it difficult (use Unique_Name or Duplicated_Name, either of which is immediately understandable).
EDIT:
If you need to restrict your selection, I recommend encapsulating the query in a view (including the ROW_NUMBER() function), and query the view. Alternatively, if your RDBMS supports it, wrap the query in a CTE. Multiple nested FROM clauses are like multiple nested if statements - confusing. Being able to logically seperate parts of the query with a view or CTE goes a long way to retaining sanity.