delimiter $$

DROP PROCEDURE IF exist drop_tables();

create procedure drop_tables()
begin
  SELECT
    @drop_sql:=concat('DROP TABLE IF EXISTS ', group_concat(table_name))
    drop_statement
  FROM information_schema.tables
  WHERE table_schema=database();
  IF (@drop_sql IS NOT NULL) THEN
    PREPARE stmt from @drop_sql;
    EXECUTE stmt;
    DROP PREPARE stmt;
  END IF;
end$$
delimiter ;