Lemon Tree is by the German band Fool's Garden, from the 1995 Universal Records release "Dish Of The Day".

I have the single, which has several club mixes as well.  Peter Freudenthaler sounds nothing like Sting.

The "Sting" version that you heard is actually a cover version by Dreams Of Paradise.  The guy does sound a little similar to Sting, but definitely not him.

Steve