“SQL Удалить дубликат” Ответ

SQL Удалить дубликаты

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.*/
Lucas Gomes

SQL DELETE Duplicate

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

SQL удалить дубликаты рядов, но сохраните один

# 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;
Upset Unicorn

SQL Удалить дубликат

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

SQL Удалить дубликаты на основе столбца

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
Mysterious Moose

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