All three of my girls (now 15, 11 and 4) were potty trained in the daytime long before they could make it through the night.
The two older ones I kept in pullups longer, and it took longer for them at night than it did my third. But--that doesn't necessarily prove anything. It could be that my third was just ready sooner.
With the older two, I finally found something that worked. (The oldest was about 8 and the youngest 3 when I did this--both still occasionally wetting).
For me the answer turned out to be this great little gadget that runs on batteries. At night, you attach it to their panties with a tiny clip and as soon as they start to wet it sounds an alarm and wakes them up. Because it brings them to a different level of sleep, they instinctively are alerted to hold it until they wake up all the way and can go in the right place! It trains them to recognise the signs during sleep so they start to wake automatically. I'm sure you could find it on the internet--I forget the name of it immediately, but if you email me I'll look for it and send it to you.
It worked for me in less than a week with both, and then I lent it to a friend for her two girls. Totally successful with hers too. Fortunately I didn't need it with my third daughter, because it was broken by then!