When does a pitcher get a winn

Question
Hi,
there are a few things i don't understand about when a pitcher gets a winn or
a loss.
For example if Jack pitches 8 innings and his team has a 2-1 lead, and then
he goes out and Ryan comes in to pitch, he allows 1 run and the game is tied.
Then Dave comes in to pitch and his team scores the go-ahead run and they
winn.
Who gets the winn? Jack or Dave?

Thanks.
Julian.

Answer
Julian,
In your example, Dave would get the Win because Jack was out of the game when the lead was lost (game was tied up 2-2).  If the team would have scored the go-ahead run while Ryan was in the game, he would have gotten credit for the Win.  Because Dave was the pitcher of record at the time his team took the lead, he gets the Win.  

Did this help?  Let me know if you have any other questions.

Donovan