使用多个连接语句完成外部连接的逻辑是什么？

Question

SELECT MP.* 
FROM SurveyFrontend..WebResult WR 
JOIN MeetingHistory MH 
ON MH.WebResultID=WR.WebResultID 
JOIN Meeting M 
ON MH.MeetingID=M.MeetingID 
JOIN MeetingPlanner MP 
ON MP.MeetingPlannerID=M.MeetingPlannerID 
WHERE PrimaryEntityID=2424 
AND WR.TimeResultTaken>='1/1/2016' 
AND CardSet=2 

我查了一下，但找不到任何有关如何用多个连接完成外部连接的示例。我想拉上面的查询完全相反。

我该怎么做呢？

这正是我在寻找：

更新代码：

SELECT MP.* 
FROM SurveyFrontend..WebResult WR 
FULL OUTER JOIN MeetingHistory MH 
ON MH.WebResultID=WR.WebResultID 
FULL OUTER JOIN Meeting M 
ON MH.MeetingID=M.MeetingID 
FULL OUTER JOIN MeetingPlanner MP 
ON MP.MeetingPlannerID=M.MeetingPlannerID 
WHERE PrimaryEntityID=2424 
AND WR.TimeResultTaken>='1/1/2016' 
AND CardSet=2 
AND (MH.WebResultID IS NULL 
OR MH.MeetingID IS NULL 
OR MP.MeetingPlannerID IS NULL 
OR WR.WebResultID IS NULL 
OR M.MeetingID IS NULL 
OR M.MeetingPlannerID IS NULL) 

Answer 1

full outer join收益匹配on条件和从左表中的所有行，所有行构成不符合条件和右表中所有来自右表的不匹配条件的行。任何where限制将full outer join减小到left，right或inner join。一些例子：

create table #a(id int, name varchar(10)) 
insert #a values (1,'test1'),(2,'test2'),(3,'test3') 
create table #b(id int, name varchar(10)) 
insert #b values (1,'test1'),(4,'test4'),(5,'test5') 

select a.id aid,a.name aname, b.id bid,b.name bname 
from #a a full outer join #b b on a.id=b.id 

--same as left join 
select a.id aid,a.name aname, b.id bid,b.name bname 
from #a a full outer join #b b on a.id=b.id 
where a.id=2 

--same as right join 
select a.id aid,a.name aname, b.id bid,b.name bname 
from #a a full outer join #b b on a.id=b.id 
where b.id=4 

--same as inner join 
select a.id aid,a.name aname, b.id bid,b.name bname 
from #a a full outer join #b b on a.id=b.id 
where a.id=1 and b.id=1 

--same as inner join better example 
select a.id aid,a.name aname, b.id bid,b.name bname 
from #a a full outer join #b b on a.id=b.id 
where a.id = b.id