CREATE TABLE IF NOT EXISTS jumps (
  player_name TEXT,
  jump_name TEXT,
  world_name TEXT,
  x REAL, y REAL, z REAL, yaw REAL,
  PRIMARY KEY (player_name, jump_name))

CREATE TABLE IF NOT EXISTS signs (
  world_name TEXT,
  x INTEGER, y INTEGER, z INTEGER,
  player_name TEXT,
  jump_name TEXT,
  PRIMARY KEY (world_name, x, y, z),
  FOREIGN KEY (player_name, jump_name)
    REFERENCES jumps (player_name, jump_name)
    ON DELETE CASCADE  ON UPDATE CASCADE)