SELECT @rownum:=@rownum+1 AS ID,
NameList.iName
FROM
(SELECT DISTINCT iName, COUNT(iName) AS iCount
FROM people
GROUP BY iName
ORDER BY iCount DESC) NameList,
(SELECT @rownum:=0) r
изменить этот подзапрос
(SELECT DISTINCT iName, COUNT(iName) AS iCount
FROM people
GROUP BY iName
ORDER BY iCount DESC)
на таблицу со списком имен.