如何找到拥有比所有用户平均“计数”高的“计数”数量的“成员”？

Question

我有两个桌子。 成员和流。 我想查找所有成员的平均流数，然后查看哪些单个成员（包括名字）流过的数据流大于平均流数。

目前，我有这个查询，可以找到平均流数和每个成员拥有的流数；

select stream.m_ID, count(*), (select avg (count(*)) from stream group by stream.m_ID) from stream group by stream.m_ID;

我正在努力寻找如何丢弃流数量少于平均数量的成员并将成员和流表连接在一起的方法

CREATE TABLE "M_5006677"."MEMBER" 
   (    "M_ID" NUMBER(2,0), 
    "FNAME" VARCHAR2(15 BYTE) NOT NULL ENABLE, 
    "MNAME" VARCHAR2(15 BYTE), 
    "LNAME" VARCHAR2(15 BYTE) NOT NULL ENABLE, 
    "EMAIL" VARCHAR2(25 BYTE) NOT NULL ENABLE, 
    "R_DATE" DATE NOT NULL ENABLE, 
    "L_DATE" DATE, 
     CONSTRAINT "PK_M_ID" PRIMARY KEY ("M_ID")

CREATE TABLE "M_5006677"."STREAM" 
   (    "STREAM_ID" NUMBER(2,0), 
    "SDATE" DATE, 
    "SPOSITION" NUMBER(5,2), 
    "F_ID" NUMBER(2,0) NOT NULL ENABLE, 
    "M_ID" NUMBER(2,0) NOT NULL ENABLE, 
    "LIVE" VARCHAR2(3 BYTE), 
     CONSTRAINT "PK_STREAM" PRIMARY KEY ("STREAM_ID")
CONSTRAINT "FK_F_ID" FOREIGN KEY ("F_ID") REFERENCE FILM
CONSTRAINT "FK_M_ID" FOREIGN KEY ("M_ID") REFERENCE MEMBER

Answer 1

我会使用窗口功能。 如果您只想统计曾经直播过的成员：

select m_id
from (select m_id, count(*) as cnt, avg(count(*)) over () as avg_overall
      from streams
      group by m_id
     ) s
where cnt > avg_overall;

如果要计算从未流过的成员：

select m_id
from (select m_id, count(*) as cnt, avg(count(s.m_id)) over () as avg_overall
      from members m left join
           streams s
           on m.m_id = s.m_id
      group by m_id
     ) s
where cnt > avg_overall;

Answer 2

这将适用于SQL Server：

select stream.m_ID, count(*), (select avg (count(*)) from stream group by stream.m_ID) from stream group by stream.m_ID 
having count(*) < (select avg (count(*)) from stream group by stream.m_ID)

如果您还希望获取有关成员的数据，则应在查询中包含M_ID，以便可以像这样与members表联接：

select stream.m_ID, M_ID, count(*), (select avg (count(*)) from stream group by stream.m_ID) from stream group by stream.m_ID ,M_ID
having count(*) < (select avg (count(*)) from stream group by stream.m_ID)

之后，您可以使用Members表加入M_ID：

select FNAME from Member m
join (select stream.m_ID, M_ID, count(*), (select avg (count(*)) from stream 
group by stream.m_ID) from stream group by stream.m_ID ,M_ID
    having count(*) < (select avg (count(*)) from stream group by 
stream.m_ID)) X on m.M_ID = X.M_ID