java 各种 树形结构构图方法和数据库函数 【非控件】

 CREATE TABLE `dept` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `deptid` int(11) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8;

INSERT INTO `dept` VALUES ('1', '语音业务部', null);
  INSERT INTO `dept` VALUES ('2', '小云AI', '1');
  INSERT INTO `dept` VALUES ('3', '云客宝', '1');
  INSERT INTO `dept` VALUES ('4', '流量业务部', null);
  INSERT INTO `dept` VALUES ('5', 'MIFI', '4');
  INSERT INTO `dept` VALUES ('6', '物联网卡', '4');

SELECT
        b.*
    FROM
        dept a
    INNER JOIN dept b ON a.id = b.deptid
    WHERE
        a.id = 1

delimiter /
    DROP FUNCTION IF EXISTS `mydb`.`getChild`/
    CREATE FUNCTION `getChild`(rootId varchar(36))
      RETURNS VARCHAR(1000)
      BEGIN
        DECLARE ptemp VARCHAR(1000);
        DECLARE ctemp VARCHAR(1000);
        SET ptemp = '#';
        SET ctemp = rootId;
        WHILE ctemp IS NOT NULL DO
          SET ptemp = concat(ptemp, ',', ctemp);
          SELECT group_concat(id)
          INTO ctemp
          FROM t_tree_table
          WHERE FIND_IN_SET(pid, ctemp) > 0;
        END WHILE;
        RETURN ptemp;
      END;