Can I extract the extract records that are duplicated in sql?

Question

In my table I have the following columns:

id|name|gender

I would like to extract all the names which are duplicated, but I don\'t want to scan

Answer 1

SELECT
   name
FROM
   Mytable
GROUP BY
   name
HAVING
   COUNT(*) > 1

To separate gender too, change the GROUP BY to name, gender

To delete duplicate rows

DELETE MyTable
WHERE ID NOT IN
   (
    SELECT
       MIN(Id)
    FROM
       Mytable
    GROUP BY
       name
   )