|You have a parties table that holds info on peoples' names etc, and a contracts table where each row has clientID and contractorID value pointing at a parties.partyID value--that is, each contracts row points at two parties rows. You want to list the names of all contractors and their clients.
pCli.name AS Client,
pCon.name AS Contractor
INNER JOIN parties AS pCli
ON contracts.clientpartyID = pCli.partyID
INNER JOIN parties AS pCon
ON contracts.contractorpartyID = pCon.partyID;