Finding data in Team Services DB

I am a newbie to TFS. I am wanting to create some of my own custom
reports from the data in our TFS database. I found the data I need in
TFSWorkItemTracking. What I can't figure out is how to I limit the
data I pull from this table based on the project?

I can't find a reference to the project in order to limit my select.
Can someone offer some help?

Thanks,
Glen

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