Oracle SQL统计各单位及其子级单位用户总数

业务场景：最近帮同事写一个sql，业务是统计各个单位及其子单位用户总数，听起来是挺容易的，所以拿起键盘就是敲：

  select sum(t.ucount)
      from (select count(1) as ucount, uinfo.unit_code, uinfo.unit_name
              from t_user bs
             inner join (select unit_code, unit_name
                          from t_unit_info
                         start with unit_code = #{unitCode}
                        connect by prior unit_code = para_unit_code) uinfo
                on bs.unit_code = uinfo.unit_code
             group by uinfo.unit_code, uinfo.unit_name) t;

不过这个只能传个顶级单位编码，一个一个查，这样肯定很耗时，所以还是自己想太简单了，摸索了好一阵子，想到方法：

①、新建一个函数，传一个顶级单位编码，通过函数统计本单位及其子单位的用户总数

create or replace function FU_UNIT_USER_COUNT(unitCode in varchar2)
  RETURN NUMBER IS
  v_Value number(9,1);
BEGIN
    select sum(t.ucount) into v_Value
      from (select count(1) as ucount, uinfo.unit_code, uinfo.unit_name
              from t_user bs
             inner join (select unit_code, unit_name
                          from lzcity_approve_unit_info
                         start with unit_code = unitCode
                        connect by prior unit_code = para_unit_code) uinfo
                on bs.unit_code = uinfo.unit_code
             group by uinfo.unit_code, uinfo.unit_name) t;
  RETURN v_Value;
END;

测试函数是否建立成功：

select FH_UNIT_USER_COUNT('15803') from dual;

②、调用函数，传顶级单位编码进行统计

select FH_UNIT_USER_COUNT(uinfo.unit_code) as 用户总数,
       uinfo.unit_code as 单位编码,
       uinfo.unit_name as 厅单位名称
  from t_unit_info uinfo
 group by uinfo.unit_code, uinfo.unit_name
 order by 用户总数 desc nulls last