REPETATION OF elements in SQL code example

Example 1: sql get rows with duplicate values

/* Gets reps */
SELECT fieldA, COUNT(*)
FROM tableA
GROUP BY fieldA
HAVING COUNT(*) > 1

/* Use reps to filter results */
SELECT a.*
FROM tableA a
JOIN (
	SELECT fieldA, COUNT(*) as 'count'
	FROM tableA
	GROUP BY fieldA
	HAVING COUNT(*) > 1
) b
ON a.fieldA = b.fieldA

Example 2: sql check double value

SELECT
    name, email, COUNT(*)
FROM
    users
GROUP BY
    name, email
HAVING 
    COUNT(*) > 1