Finding duplicate rows in SQL Server
SqlSql ServerDuplicatesSql Problem Overview
I have a SQL Server database of organizations, and there are many duplicate rows. I want to run a select statement to grab all of these and the amount of dupes, but also return the ids that are associated with each organization.
A statement like:
SELECT orgName, COUNT(*) AS dupes
FROM organizations
GROUP BY orgName
HAVING (COUNT(*) > 1)
Will return something like
orgName | dupes
ABC Corp | 7
Foo Federation | 5
Widget Company | 2
But I'd also like to grab the IDs of them. Is there any way to do this? Maybe like a
orgName | dupeCount | id
ABC Corp | 1 | 34
ABC Corp | 2 | 5
...
Widget Company | 1 | 10
Widget Company | 2 | 2
The reason being that there is also a separate table of users that link to these organizations, and I would like to unify them (therefore remove dupes so the users link to the same organization instead of dupe orgs). But I would like part manually so I don't screw anything up, but I would still need a statement returning the IDs of all the dupe orgs so I can go through the list of users.
Sql Solutions
Solution 1 - Sql
select o.orgName, oc.dupeCount, o.id
from organizations o
inner join (
SELECT orgName, COUNT(*) AS dupeCount
FROM organizations
GROUP BY orgName
HAVING COUNT(*) > 1
) oc on o.orgName = oc.orgName
Solution 2 - Sql
You can run the following query and find the duplicates with max(id) and delete those rows.
SELECT orgName, COUNT(*), Max(ID) AS dupes
FROM organizations
GROUP BY orgName
HAVING (COUNT(*) > 1)
But you'll have to run this query a few times.
Solution 3 - Sql
You can do it like this:
SELECT
o.id, o.orgName, d.intCount
FROM (
SELECT orgName, COUNT(*) as intCount
FROM organizations
GROUP BY orgName
HAVING COUNT(*) > 1
) AS d
INNER JOIN organizations o ON o.orgName = d.orgName
If you want to return just the records that can be deleted (leaving one of each), you can use:
SELECT
id, orgName
FROM (
SELECT
orgName, id,
ROW_NUMBER() OVER (PARTITION BY orgName ORDER BY id) AS intRow
FROM organizations
) AS d
WHERE intRow != 1
Edit: SQL Server 2000 doesn't have the ROW_NUMBER() function. Instead, you can use:
SELECT
o.id, o.orgName, d.intCount
FROM (
SELECT orgName, COUNT(*) as intCount, MIN(id) AS minId
FROM organizations
GROUP BY orgName
HAVING COUNT(*) > 1
) AS d
INNER JOIN organizations o ON o.orgName = d.orgName
WHERE d.minId != o.id
Solution 4 - Sql
You can try this , it is best for you
WITH CTE AS
(
SELECT *,RN=ROW_NUMBER() OVER (PARTITION BY orgName ORDER BY orgName DESC) FROM organizations
)
select * from CTE where RN>1
go
Solution 5 - Sql
The solution marked as correct didn't work for me, but I found this answer that worked just great: https://stackoverflow.com/questions/2881774/get-list-of-duplicate-rows-in-mysql
SELECT n1.*
FROM myTable n1
INNER JOIN myTable n2
ON n2.repeatedCol = n1.repeatedCol
WHERE n1.id <> n2.id
Solution 6 - Sql
If you want to delete duplicates:
WITH CTE AS(
SELECT orgName,id,
RN = ROW_NUMBER()OVER(PARTITION BY orgName ORDER BY Id)
FROM organizations
)
DELETE FROM CTE WHERE RN > 1
Solution 7 - Sql
select * from [Employees]
For finding duplicate Record 1)Using CTE
with mycte
as
(
select Name,EmailId,ROW_NUMBER() over(partition by Name,EmailId order by id) as Duplicate from [Employees]
)
select * from mycte
2)By Using GroupBy
select Name,EmailId,COUNT(name) as Duplicate from [Employees] group by Name,EmailId
Solution 8 - Sql
Select * from (Select orgName,id,
ROW_NUMBER() OVER(Partition By OrgName ORDER by id DESC) Rownum
From organizations )tbl Where Rownum>1
So the records with rowum> 1 will be the duplicate records in your table. ‘Partition by’ first group by the records and then serialize them by giving them serial nos. So rownum> 1 will be the duplicate records which could be deleted as such.
Solution 9 - Sql
select column_name, count(column_name)
from table_name
group by column_name
having count (column_name) > 1;
Solution 10 - Sql
select a.orgName,b.duplicate, a.id
from organizations a
inner join (
SELECT orgName, COUNT(*) AS duplicate
FROM organizations
GROUP BY orgName
HAVING COUNT(*) > 1
) b on o.orgName = oc.orgName
group by a.orgName,a.id
Solution 11 - Sql
select orgname, count(*) as dupes, id
from organizations
where orgname in (
select orgname
from organizations
group by orgname
having (count(*) > 1)
)
group by orgname, id
Solution 12 - Sql
You have several way for Select duplicate rows.
for my solutions , first consider this table for example
CREATE TABLE #Employee
(
ID INT,
FIRST_NAME NVARCHAR(100),
LAST_NAME NVARCHAR(300)
)
INSERT INTO #Employee VALUES ( 1, 'Ardalan', 'Shahgholi' );
INSERT INTO #Employee VALUES ( 2, 'name1', 'lname1' );
INSERT INTO #Employee VALUES ( 3, 'name2', 'lname2' );
INSERT INTO #Employee VALUES ( 2, 'name1', 'lname1' );
INSERT INTO #Employee VALUES ( 3, 'name2', 'lname2' );
INSERT INTO #Employee VALUES ( 4, 'name3', 'lname3' );
First solution :
SELECT DISTINCT *
FROM #Employee;
WITH #DeleteEmployee AS (
SELECT ROW_NUMBER()
OVER(PARTITION BY ID, First_Name, Last_Name ORDER BY ID) AS
RNUM
FROM #Employee
)
SELECT *
FROM #DeleteEmployee
WHERE RNUM > 1
SELECT DISTINCT *
FROM #Employee
Secound solution : Use identity field
SELECT DISTINCT *
FROM #Employee;
ALTER TABLE #Employee ADD UNIQ_ID INT IDENTITY(1, 1)
SELECT *
FROM #Employee
WHERE UNIQ_ID < (
SELECT MAX(UNIQ_ID)
FROM #Employee a2
WHERE #Employee.ID = a2.ID
AND #Employee.FIRST_NAME = a2.FIRST_NAME
AND #Employee.LAST_NAME = a2.LAST_NAME
)
ALTER TABLE #Employee DROP COLUMN UNIQ_ID
SELECT DISTINCT *
FROM #Employee
and end of all solution use this command
DROP TABLE #Employee
Solution 13 - Sql
i think i know what you need i needed to mix between the answers and i think i got the solution he wanted:
select o.id,o.orgName, oc.dupeCount, oc.id,oc.orgName
from organizations o
inner join (
SELECT MAX(id) as id, orgName, COUNT(*) AS dupeCount
FROM organizations
GROUP BY orgName
HAVING COUNT(*) > 1
) oc on o.orgName = oc.orgName
having the max id will give you the id of the dublicate and the one of the original which is what he asked for:
id org name , dublicate count (missing out in this case)
id doublicate org name , doub count (missing out again because does not help in this case)
only sad thing you get it put out in this form
id , name , dubid , name
hope it still helps
Solution 14 - Sql
Suppose we have table the table 'Student' with 2 columns:
-
student_id int -
student_name varcharRecords: +------------+---------------------+ | student_id | student_name | +------------+---------------------+ | 101 | usman | | 101 | usman | | 101 | usman | | 102 | usmanyaqoob | | 103 | muhammadusmanyaqoob | | 103 | muhammadusmanyaqoob | +------------+---------------------+
Now we want to see duplicate records Use this query:
select student_name,student_id ,count(*) c from student group by student_id,student_name having c>1;
+---------------------+------------+---+
| student_name | student_id | c |
+---------------------+------------+---+
| usman | 101 | 3 |
| muhammadusmanyaqoob | 103 | 2 |
+---------------------+------------+---+
Solution 15 - Sql
I got a better option to get the duplicate records in a table
SELECT x.studid, y.stdname, y.dupecount
FROM student AS x INNER JOIN
(SELECT a.stdname, COUNT(*) AS dupecount
FROM student AS a INNER JOIN
studmisc AS b ON a.studid = b.studid
WHERE (a.studid LIKE '2018%') AND (b.studstatus = 4)
GROUP BY a.stdname
HAVING (COUNT(*) > 1)) AS y ON x.stdname = y.stdname INNER JOIN
studmisc AS z ON x.studid = z.studid
WHERE (x.studid LIKE '2018%') AND (z.studstatus = 4)
ORDER BY x.stdname
Result of the above query shows all the duplicate names with unique student ids and number of duplicate occurances
Solution 16 - Sql
/*To get duplicate data in table */
SELECT COUNT(EmpCode),EmpCode FROM tbl_Employees WHERE Status=1
GROUP BY EmpCode HAVING COUNT(EmpCode) > 1
Solution 17 - Sql
I use two methods to find duplicate rows. 1st method is the most famous one using group by and having. 2nd method is using CTE - Common Table Expression.
As mentioned by @RedFilter this way is also right. Many times I find CTE method is also useful for me.
WITH TempOrg (orgName,RepeatCount)
AS
(
SELECT orgName,ROW_NUMBER() OVER(PARTITION by orgName ORDER BY orgName)
AS RepeatCount
FROM dbo.organizations
)
select t.*,e.id from organizations e
inner join TempOrg t on t.orgName= e.orgName
where t.RepeatCount>1
In the example above we collected the result by finding repeat occurrence using ROW_NUMBER and PARTITION BY. Then we applied where clause to select only rows which are on repeat count more than 1. All the result is collected CTE table and joined with Organizations table.
Source : CodoBee
Solution 18 - Sql
Try
SELECT orgName, id, count(*) as dupes
FROM organizations
GROUP BY orgName, id
HAVING count(*) > 1;