[µo°Ý] MS SQL full join°ÝÃD full, join

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--MS SQL full join°ÝÃD
declare @t1 table (f1 nvarchar(50), f2 nvarchar(50))
declare @t2 table (f1 nvarchar(50), f3 nvarchar(50))
declare @t3 table (f1 nvarchar(50), f4 nvarchar(50))
insert into @t1 (f1,f2) values ('a','1')
insert into @t1 (f1,f2) values ('c','2')
insert into @t1 (f1,f2) values ('d','3')
insert into @t2 (f1,f3) values ('a','4')
insert into @t2 (f1,f3) values ('b','5')
insert into @t2 (f1,f3) values ('d','6')
insert into @t3 (f1,f4) values ('c','7')
insert into @t3 (f1,f4) values ('e','8')
--select t1f1=t1.f1,t2f1=t2.f1,t3f1=t3.f1,f2,f3,f4
select f1=isnull(t1.f1,isnull(t2.f1,t3.f1)),f2,f3,f4
from @t1 t1
full join @t2 t2 on t1.f1=t2.f1
full join @t3 t3 on t2.f1=t3.f1
order by f1
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select f1=isnull(t1.f1,isnull(t2.f1,t3.f1)),f2,f3,f4
from @t1 t1
full join @t2 t2 on t1.f1=t2.f1
full join @t3 t3 on t1.f1=t3.f1
order by f1
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https://drive.google.com/file/d/0B43q2SqHw8xcUlRZVnZuaHViUjQ/view