查询以从3个不同的表获取数据以获取具有计数的不同键

Question

用户表

userName | email(p.k) | accountType(p.k)

Vivek    | v@asd.asd  | google
Rahul    | r@asd.asd  | facebook
Rohit    | r@amd.asd  | google

事件表

eventId(p.k) | email(f.k) | accountType(f.k) | eventName

    1        | v@asd.asd  |      google      | birthday

贡献者

eventId(f.k) | email(f.k) | accountType(f.k) | contribute

    1        | r@asd.asd  |     facebook     |     $20
    1        | r@amd.asd  |      google      |     $30

我想要类似的结果数据

结果

userName contribute  name    count  eventName
 Rahul       $20     Vivek     2    birthday
 Rohit       $30     Vivek     2    birthday


rahul contribute $20 for vivek birthday 2 contributer are there for this event
rohit contribute $30 for vivek birthday 2 contributer are there for this event

查询我的用途

SELECT 
uc.userName as cName, 
uc.email as cEmail, 
uc.accountType as cAccType,
contribute, 
u.userName as userName,
u.email as email, 
u.accountType as accountType,
eventName 
FROM user u 
join event e on u.email=e.email and u.accountType=e.accountType 
join contributer c on c.eventId=e.eventId 
join user uc on c.email=uc.email and c.accountType=uc.accountType

和类似的东西

SELECT * 
FROM user
JOIN contribute ON user.email = contribute.email
JOIN event ON event.id = contribute._eventId
JOIN user u2 ON event.email = u2.email;

如何在同一个查询中同时获取带有计数的两个数据，任何人都可以帮助我

Answer 1

使用子查询：

    select user_name,(select contribute from contributer   
     where email = usr.email) as contribute,(select user_name from user_table where email = (select email   
    from event_table where event_id = (select event_id from contributer where email = usr.email))) as name,(select count(event_id) from contributer 
where event_id = (select event_id from contributer 
where email = usr.email)) as count from user_table as usr

结果：

userName contribute  name    count

Vivek     NULL        NULL    0

Rahul     $20         Vivek   2

Rohit     $30         Vivek   2

Answer 2

由于用户在结果中出现两次，因此您必须使用该表两次-一次作为贡献者，另一次作为在庆祝活动中受到嘉奖的人。

类似这样的东西（Oracle）：

SQL> with t_user (username, email, accounttype) as
  2    (select 'vivek', 'v@asd.asd', 'google'       from dual union
  3     select 'rahul', 'r@asd.asd', 'facebook'     from dual union
  4     select 'rohit', 'r@amd.asd', 'google'       from dual
  5    ),
  6  t_event (eventid, email, accounttype, eventname) as
  7    (select 1, 'v@asd.asd', 'google', 'birthday' from dual),
  8  t_contributer (eventid, email, accounttype, contribute) as
  9    (select 1, 'r@asd.asd', 'facebook', '$20'    from dual union
 10     select 1, 'r@amd.asd', 'google'  , '$30'    from dual)
 11  select
 12    t1.username || ' contribute ' ||      c.contribute   ||
 13    ' for '     || t2.username    ||' '|| e.eventname    ||' ' ||
 14    count(*) over (partition by c.eventid order by null) ||
 15    ' contributer for this week' result
 16  from t_contributer c join t_event e on c.eventid = e.eventid
 17  join t_user t1 on t1.email = c.email
 18  join t_user t2 on t2.email = e.email;

RESULT
--------------------------------------------------------------------------------
rahul contribute $20 for vivek birthday 2 contributer for this week
rohit contribute $30 for vivek birthday 2 contributer for this week

SQL>

Answer 3

通过添加（从贡献者中选择count（eventId），其中eventId = e.eventId），对我有很大帮助。

SELECT 
uc.userName as cName, 
uc.email as cEmail, 
uc.accountType as cAccType,
c.contribute, 
u.userName as userName,
u.email as email, 
u.accountType as accountType,
e.eventName ,
(select count(eventId) from contributor where eventId = e.eventId)
FROM user u 
join event e on u.email=e.email and u.accountType=e.accountType 
join contributer c on c.eventId=e.eventId 
join user uc on c.email=uc.email and c.accountType=uc.accountType