如何获得列之间的唯一组合？

Question

table喜欢：

F    G
---- ----
123  ABC
ABC  123
DEF  123

我需要获得：

F    G
---- ----
123  ABC
DEF  123

Answer 1

这是你想要的吗？

select min(f), max(g)
from t
group by (case when f < g then f else g end),
         (case when f < g then g else f end);

Answer 2

此 CTE 匹配 f/g 和 g/f 匹配（仅保留一个匹配）和非匹配的并集：

Create Table #tbl
(
F VarChar(10),
G VarChar(10)
)

Insert Into #tbl Values
('123','ABC'),
('ABC','123'),
('DEF','123'),
('123','DEF'),
('123','XYZ')

With CTE As
(
   Select  x.F, x.G, Row_Number() Over (Order By (Select Null)) As rn
   From #tbl x 
   inner Join #tbl y On x.F = y.G And x.G = y.F
) ,
CTE1 As
(
   Select  x.F, x.G
   From #tbl x 
   left Join #tbl y On x.F = y.G And x.G = y.F
   Where y.F  Is Null
)
   Select F,G From CTE Where rn % 2 <> 0 
     Union All 
   Select F,G From CTE1

结果：

F   G
ABC 123
123 DEF
123 XYZ

如何获得列之间的唯一组合？

How to get unique combinations between columns?

sql

tsql

sql-server

sql-server-2014