SQL

Query to remove duplicate rows from a table

DELETE FROM Customers WHERE ROWID(SELECT MAX (rowid) FROM Customers C WHERE CustomerNumber = C.CustomerNumber);

sql remove duplicates

WITH cte AS (
    SELECT 
        contact_id, 
        first_name, 
        last_name, 
        email, 
        ROW_NUMBER() OVER (
            PARTITION BY 
                first_name, 
                last_name, 
                email
            ORDER BY 
                first_name, 
                last_name, 
                email
        ) row_num
     FROM 
        sales.contacts
)
DELETE FROM cte
WHERE row_num > 1;
/*
Code language: SQL (Structured Query Language) (sql)

In this statement:

First, the CTE uses the ROW_NUMBER() function to find the duplicate rows 
specified by values in the first_name, last_name, and email columns.

Then, the DELETE statement deletes all the duplicate rows but keeps only one 
occurrence of each duplicate group.*/

sql delete duplicate rows

WITH cte AS (
    SELECT 
        contact_id, 
        first_name, 
        last_name, 
        email, 
        ROW_NUMBER() OVER (
            PARTITION BY 
                first_name, 
                last_name, 
                email
            ORDER BY 
                first_name, 
                last_name, 
                email
        ) row_num
     FROM 
        sales.contacts
)
DELETE FROM cte
WHERE row_num > 1;

sql delete duplicate

-- Oracle
DELETE FROM films
WHERE rowid NOT IN (
    SELECT min(rowid)
    FROM films
    GROUP BY title, uk_release_date
);

SQL remove duplicate

DELETE FROM [SampleDB].[dbo].[Employee]
    WHERE ID NOT IN
    (
        SELECT MAX(ID) AS MaxRecordID
        FROM [SampleDB].[dbo].[Employee]
        GROUP BY [FirstName], 
                 [LastName], 
                 [Country]
    );

DELETE DUPLICATE VALUES FROM A TABLE IN SQL SERVER

WITH cte AS (
    SELECT 
        contact_id, 
        first_name, 
        last_name, 
        email, 
        ROW_NUMBER() OVER (
            PARTITION BY 
                first_name, 
                last_name, 
                email
            ORDER BY 
                first_name, 
                last_name, 
                email
        ) row_num
     FROM 
        sales.contacts
)
DELETE FROM cte
WHERE row_num > 1;
Code language: SQL (Structured Query Language) (sql)

sql delete duplicate rows but keep one

# Step 1: Copy distinct values to temporary table
CREATE TEMPORARY TABLE tmp_user (
    SELECT id, name 
    FROM user
    GROUP BY name
);

# Step 2: Remove all rows from original table
DELETE FROM user;

# Step 3: Remove all rows from original table
INSERT INTO user (SELECT * FROM tmp_user);

# Step 4: Remove temporary table
DROP TABLE tmp_user;

sql query to delete duplicate records

--ID should be primary key

--get duplicate records using RANK
SELECT E.ID, 
    E.firstname, 
    E.lastname, 
    E.country, 
    T.rank
FROM [SampleDB].[dbo].[Employee] E
  INNER JOIN
(
 SELECT *, 
        RANK() OVER(PARTITION BY firstname, 
                                 lastname, 
                                 country
        ORDER BY id) rank
 FROM [SampleDB].[dbo].[Employee]
) T ON E.ID = t.ID;

--delete duplications
DELETE E
    FROM [SampleDB].[dbo].[Employee] E
         INNER JOIN
    (
        SELECT *, 
               RANK() OVER(PARTITION BY firstname, 
                                        lastname, 
                                        country
               ORDER BY id) rank
        FROM [SampleDB].[dbo].[Employee]
    ) T ON E.ID = t.ID
    WHERE rank > 1;

sql remove duplicates based on column

SELECT s.siteName, s.siteIP, h.date
FROM sites s INNER JOIN
     (select h.*, row_number() over (partition by siteName order by date desc) as seqnum
      from history h
     ) h
    ON s.siteName = h.siteName and seqnum = 1
ORDER BY s.siteName, h.date

delete duplicate sql

WITH CTE AS(
   SELECT [col1]
           ,[col2]
           ,[col3]
     ,
       RN = ROW_NUMBER()OVER(PARTITION BY [col1],[col2],[col3] ORDER BY [col1],[col2],[col3])
   FROM [dbo].[table1]

)
DELETE FROM CTE WHERE RN > 1

sql script to delete duplicate records in a table

WITH CTE([FirstName], 
    [LastName], 
    [Country], 
    DuplicateCount)
AS (SELECT [FirstName], 
           [LastName], 
           [Country], 
           ROW_NUMBER() OVER(PARTITION BY [FirstName], 
                                          [LastName], 
                                          [Country]
           ORDER BY ID) AS DuplicateCount
    FROM [SampleDB].[dbo].[Employee])
DELETE FROM CTE
WHERE DuplicateCount > 1;
/*will delete the duplicate value*/