In this paper, a concurrent execution of a transaction in a peer to peer database network is investigated. A peer to peer database network is nothing but a collection of peers connected in a network which shares the databases for the sake of convenience with an interoperability layer (i.e. mapping). In a network all the peers manages its own conventional databases and executes a queer and updates the related data in other peers also. It also joins the databases from one or more peer and form its own materialized view.