Java查询每个部门总人数（包含每个部门层级的总数）

需求：最近需要统计每个部门的用户数量，最开始想的比较简单，通过部门id去查询，结果忘记了部门下面有子集部门，这样通过一般的条件查询就只能查出当前部门的人数。而不能查询当前部门下面包含了子集部门的人数，查询方法如下：

1.用递归的方式查询出部门树

2.在递归里面通过部门节点路径来后模糊查询

3.完整代码分享

MYSQL库表设计：

用户表和角色表就行了，用户角色关联表这里用不上

CREATE TABLE `org` (
  `id` bigint unsigned NOT NULL COMMENT '主键id',
  `name` varchar(50) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '组织机构名称',
  `parent_id` bigint unsigned NOT NULL DEFAULT '0' COMMENT '上级机构id',
  `level` smallint unsigned NOT NULL DEFAULT '1' COMMENT '树节点层级',
  `node_path` varchar(512) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '节点路径',
  `status` tinyint unsigned NOT NULL DEFAULT '1' COMMENT '状态值;启用1是0否',
  `sort_no` smallint unsigned NOT NULL DEFAULT '10' COMMENT '排序号;规则升序',
  PRIMARY KEY (`id`) USING BTREE
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci COMMENT='组织机构表';

CREATE TABLE `user` (
  `id` bigint unsigned NOT NULL COMMENT '主键',
  `username` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '用户名',
  `cname` varchar(20) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '中文名',
  `password` varchar(40) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci NOT NULL COMMENT '密码',
  `id_number` char(18) CHARACTER SET utf8mb4 COLLATE utf8mb4_icelandic_ci DEFAULT NULL COMMENT '身份证号',
  `phone_number` char(11) CHARACTER SET utf8mb4 COLLATE utf8mb4_general_ci DEFAULT NULL COMMENT '手机号',
  `status` tinyint unsigned DEFAULT '1' COMMENT '状态值;1启用0禁用',
  `updated` datetime DEFAULT CURRENT_TIMESTAMP COMMENT '更新时间',
  `org_id` bigint unsigned DEFAULT '1000' COMMENT '机构id',
  `sort` smallint DEFAULT '10' COMMENT '排序号',
  PRIMARY KEY (`id`) USING BTREE,
  UNIQUE KEY `uk_username` (`username`) USING BTREE,
  UNIQUE KEY `uk_phone_number` (`phone_number`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_general_ci COMMENT='用户表';

主要代码：

   /**
     * 获取组织机构树
     * @return
     */
    public List<OrgTreeNode> tree() {
        List<Org> all = this.loadAll();
        if (CollectionUtil.isEmpty(all)) {
            return Collections.emptyList();
        }

        List<OrgTreeNode> roots = getRoot(all);
        if (CollectionUtil.isEmpty(roots)) {
            return Collections.emptyList();
        }
        for (OrgTreeNode root : roots) {
            root.setChildren(getChildren(all, root.getId()));
        }
        return roots;
    }

/**
     * 递归查询子节点
     *
     * @param all      所有节点
     * @param parentId 父节点id
     * @return
     */
    private List<OrgTreeNode> getChildren(List<Org> all, Long parentId) {
        List<OrgTreeNode> children = all.stream()
                .filter(org -> Objects.equals(org.getParentId(), parentId))
                .map(org -> {
                    OrgTreeNode node = new OrgTreeNode();
                    BeanUtils.copyProperties(org, node);
                    node.setChildren(getChildren(all, node.getId()));
                    return node;
                }).collect(Collectors.toList());
        //查询当前部门用户人数
        for (int i = 0; i < children.size(); i++) {
            //根据部门节点查询当前部门用户数量
            int userNum = baseMapper.countUserNumOrgId(children.get(i).getNodePath());
            children.get(i).setEstablishmentNumber(userNum);
        }
        if (CollectionUtil.isEmpty(children)) {
            return Collections.emptyList();
        } else {
            return children;
        }
    }

/**
     * 根据部门节点统计当前部门用户数量
     * @param orgNodePath
     * @return
     */
    @Select("SELECT COUNT(*) AS total_count FROM USER u LEFT JOIN org o ON u.org_id = o.id WHERE o.node_path LIKE '${orgNodePath}%' AND o.id IS NOT NULL;")
    int countUserNumOrgId(@Param("orgNodePath") String orgNodePath);