USE DatabaseB
GO
SELECT * from DatabaseB.User.TableA
GO

USE DatabaseA
GO
SELECT * from DatabaseB.User.TableA
GO

GRANT SELECT ON DatabaseB.User.TableA to User2

grantor | grantee | type    | action   | object   | column | grantable
'User'  | 'User2' | 'Grant' | 'Select' | 'TableA' | 'All'  | 'FALSE'