[Vince]

Not quite correct. If a player can be a member of only ONE faction at a time then you need a column (factionId) in your player table that is a reference to the faction table (id column). The 'leader' column in the faction table goes in the opposite direction and is a reference to the player table.

If a player can be a member of multiple factions at the same time, consult my association table tutorial, linked in my signature.