filter duplicate data in mysql code example

Example 1: mysql remove duplicates

DELETE FROM table_name WHERE id 
       NOT IN ( SELECT id FROM table_name 
                   GROUP BY field_1, field_2)

Example 2: mysql delete duplicate rows but keep one

DELETE c1 FROM contacts c1
INNER JOIN contacts c2 
WHERE
    c1.id > c2.id AND 
    c1.email = c2.email;

Example 3: how to delete all duplicate items in mysql

DELETE FROM FriendsData WHERE fID 
       NOT IN ( SELECT fID FROM FriendsData 
                   GROUP BY UserID, FriendsUserID, IsSpecial, CreatedBy)

Example 4: mysql delete duplicate rows except one

DELETE FROM NAMES
 WHERE id NOT IN (SELECT * 
                    FROM (SELECT MIN(n.id)
                            FROM NAMES n
                        GROUP BY n.name) x)

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Sql Example

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