Eugene Mosyukov

SELECT * 
FROM `accounts` 
WHERE `pRegIP` IN (
    SELECT `pRegIP` 
    FROM `accounts`
    GROUP BY `pRegIP` 
    HAVING COUNT(*) > 1
)

SELECT SUM(cnt) FROM (
	SELECT COUNT(*) as cnt FROM users_data WHERE private='0'
	UNION
	SELECT COUNT(*) as cnt FROM deleted WHERE private='0'
	UNION
	SELECT COUNT(*) as cnt FROM mails WHERE private='0'
) u;

SELECT data.* 
FROM userData AS data
JOIN (
	SELECT id, MAX(dataTime) AS dataTime
	FROM userData
	WHERE id IN (1, 222, 333, 444, 555)
	GROUP BY id
) AS max USING (id, dataTime);

SELECT `id`, `value`
FROM  `table` 
GROUP BY  `value`;