Vous pouvez utiliser la fonction PARSENAME comme suit :
with address as(
select '192.168.1.1' as IpAddress
Union
select '192.168.1.2' as IpAddress
Union
select '192.168.1.3' as IpAddress
)
SELECT PARSENAME(IpAddress,4) as first,
PARSENAME(IpAddress,3) as second,
PARSENAME(IpAddress,2) as third,
PARSENAME(IpAddress,1) as fourth,
FROM address
La fonction PARSENAME renvoie la partie spécifiée d'un nom d'objet.