SQL Server 2008 R2：查找column1中存在column2值的行

Question

I want to find the entries where col2 record present in col1.

Table:

CREATE TABLE Test_Table
(
    Col1 int,
    Col2 int
);

Entries:

INSERT INTO Test_Table VALUES(111,112),
                              (112,113),
                              (114,115),
                              (116,117),
                              (117,118),
                              (118,119);

Expected Result:

Col1    Col2
-------------
111     112
112     113
116     117
117     118
118     119

Note: Record 114,115 not displyed because 115 is not present in col1 .

My try:

WITH CTE1
AS
(
    SELECT Col1, Col2
    FROM Test_Table
),
CTE2
AS
(
    SELECT t.Col1, t.Col2
    FROM Test_Table t
    INNER JOIN CTE1 s1
    ON s1.Col2 = t.Col1
    OR s1.Col2 = t.Col2
)
SELECT DISTINCT * FROM CTE2;

But getting all records.

Answer 1

I think this is what you want.

select t.*
from #test_table t
where exists (select 1
              from #test_table t2
              where t2.col1 = t.col2
             )
   or exists (select 1
              from #test_table t3
              where t3.col2 = t.col1
             );

Answer 2

This might also work

select t.* 
from   Test_Table t
where  exists (select 1
               from   test_table t2
               where  t2.col1 = t.col2 or t2.Col2 = t.Col1
              )

Answer 3

I think you just want exists :

select tt.*
from test_table tt
where exists (select 1
              from test_table tt2
              where tt2.col1 = tt.col2
             );

Answer 4

Using CROSS JOIN :

select t1.* from test_table t1 CROSS JOIN test_table t2
on t1.col1 = t2.col2 
UNION 
select t1.* from test_table t1 CROSS JOIN test_table t2
on t1.col2 = t2.col1 

Answer 5

Based on your comments, I suspect you want either col1/col2 to exist at another row's either col1/col2

select tt.*
from test_table tt
where exists (select 1
              from test_table tt2
              where   -- Ensure not same row
                    (tt2.col1 <> tt.col1 or tt2.col2 <> tt.col2)
                and -- Ensure at least one match
                    (tt2.col1 = tt.col1 or tt2.col1 = tt.col2 or tt2.col2 = tt.col1 or tt2.col2 = tt.col2)
             );

Answer 6

select t1.* from Test_Table t1 left join Test_Table t2 on t2.Col1=t1.Col2 where t2.Col2 is not null
union
select t1.* from Test_Table t1 left join Test_Table t2 on t2.Col2=t1.Col1 where t2.Col1 is not null