select duplicates in sql

1SELECT username, email, COUNT(*)
2FROM users
3GROUP BY username, email
4HAVING COUNT(*) > 1
5

1SELECT name, COUNT(email) 
2FROM users
3GROUP BY email
4HAVING COUNT(email) > 1

1/* Gets reps */
2SELECT fieldA, COUNT(*)
3FROM tableA
4GROUP BY fieldA
5HAVING COUNT(*) > 1
6
7/* Use reps to filter results */
8SELECT a.*
9FROM tableA a
10JOIN (
11	SELECT fieldA, COUNT(*) as 'count'
12	FROM tableA
13	GROUP BY fieldA
14	HAVING COUNT(*) > 1
15) b
16ON a.fieldA = b.fieldA
17

1• SELECT first_name, COUNT (first_name) FROM employees
2GROUP BY first_name
3HAVING (COUNT(first_name) > 1);