how to check for duplicate values in sql code example

Example 1: select duplicates in sql

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

Example 2: sql query to find duplicates in column

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

Example 3: 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 4: how to get duplicate elements in sql

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