def __str__(self):
        return self.sql_statement.sql()
Called (via the distributor) when a user joins a room. This funciton
dataset/ETHPy150Open coursera/dataduct/dataduct/database/relation.py/Relation.__str__--crossover with--dataset/ETHPy150Open matrix-org/synapse/synapse/handlers/presence.py/PresenceHandler.user_joined_room