SQL Select Between Two tables - sql

Question

I have these two tables:
T1:
ref || Name
===========
1 || A
2 || B
3 || C
4 || D
5 || E
And
T2:
ref || Name
===========
1 || w
2 || x
6 || y
7 || z
I need this result:
Name1 || Name2
==============
A || w
B || x
C || y
D || z
E || NULL
I mean some kind of full outer join, on column ref, that will not produce NULL value until there is not any record.
The priority of join is with the values that have same ref, and if row count of tables are not equal, there are some NULL results

Answer 1

Use UPD: here is how you may combine values by values count from different tables:
with t1_values as (
SELECT
name,
row_number() over (order by ref) as position
FROM #t1
),
t2_values as (
SELECT
name,
row_number() over (order by ref) as position
FROM #t2
)
SELECT
t1_values.name as name1,
t2_values.name as name2
FROM t1_values
left JOIN t2_values on t1_values.position = t2_values.position

Answer 2

This is very complicated. You want rows that match to match. Then you want unmatched rows to match unmatched rows by position, and then everything else.
with matches as (
select distinct t1.ref
from t1
where exists (select 1 from t2 where t2.ref = t1.ref)
),
tt1 as (
select t1.*, m.ref as match_ref,
row_number() over (partition by m.ref order by t1.ref) as alt_ref
from t1 left join
matches m
on t1.ref = m.ref
),
tt2 as (
select t2.*, m.ref as match_ref,
row_number() over (partition by m.ref order by t2.ref) as alt_ref
from t2 left join
matches m
on t2.ref = m.ref
)
select tt1.name, tt2.name
from tt1 left join
tt2
on tt1.match_ref = tt2.match_ref or
(tt1.match_ref is null and tt2.match_ref is null and tt1.alt_ref = tt2.alt_ref);
Here is the idea. For each row in both tables, add two new columns:
match_ref is ref when ref exists in the other table.
alt_ref is an enumerated column for the ref values that do not match.
Once you have these columns, it is possible to join the tables together, by first checking match_ref and then -- if that is not present -- checking alt.ref.
SQL Fiddle does not appear to be working for SQL Server. However, here is an identical Postgres version that does work. Here is a working version using SQL Server (this is identical to the Postgres version).

Answer 3

A look at your Question
Correct me if I am wrong, but you have two tables that have an reference ID column of names that you wish to return results sets....only, you do not say distinct so you might end up with extras.
...some kind of full outer join, on column ref, that will not
produce NULL value until there is not any record..
The priority of the JOIN is with the values that have same ref, and if row count of tables are
not equal, there are some NULL results
Actually, the result is not really deterministic. Anyways, this question is still too vague. However, I think you really just want rows matching columns to appear together and anything not....well, not. But return everything.
So, if you know which side is larger, try this:
WITH C AS (SELECT DENSE_RANK() OVER (PARTITION BY ref ORDER BY NAME DESC) AS ROW_ID
, ref
, Name AS Name1
FROM T1)
SELECT Name1, B.Name2
FROM C
LEFT OUTER JOIN (SELECT DENSE_RANK() (OVER PARTITION BY ref ORDER BY NAME DESC) AS ROW_ID
, ref
, Name AS Name2) B ON B.Row_ID = C.Row_ID AND B.ref = C.ref
Each of the ref columns have a distinct ID to attach with. It is done in consecutive order, so if there is still an issue, well, you can figure that logic out. But I'm sure this will help you tremendously get where you are wanting. :)

Answer 4

Thank you every body and excuse me if I speak badly sometimes, count it on my fatigue because of hours working.
I think I couldn't say my meaning correctly, so I answered my own question. this is not the best answer and it is not optimized, I know, but it works!
SELECT t.ref,
t.NAME AS n1,
t2.NAME AS n2
INTO #tbl1
FROM #T1 AS t
LEFT JOIN #T2 AS t2
ON t2.ref = t.ref
WHERE t2.ref IS NOT NULL
SELECT ROW_NUMBER() OVER(ORDER BY t.NAME) AS rn,
*
INTO #tbl2
FROM #T1 AS t
WHERE t.ref NOT IN (SELECT ref
FROM #tbl1)
SELECT ROW_NUMBER() OVER(ORDER BY t.NAME) AS rn,
*
INTO #tbl3
FROM #T2 AS t
WHERE t.ref NOT IN (SELECT ref
FROM #tbl1)
SELECT n1,
n2
FROM #tbl1
UNION
SELECT t1.NAME AS n1,
t2.NAME AS n2
FROM #tbl2 t1
FULL OUTER JOIN #tbl3 t2
ON t1.rn = t2.rn