SQL JOIN：存在匹配项时，从LEFT和RIGHT表返回行

Question

I have a #tmp table, and I need to find all records from the LEFT table and from the RIGHT table that have a matching Name and Coverage.

-- select * from #tmp
--#tmp table
ID  Name  IsConverted  Coverage  EarliestPolicyEffectiveDate
1   abc   1            Test1     9/1/2017
2   abc   0            Test1     9/2/2017
3   abc   0            Auto      9/3/2017
4   xyz   0            Home      9/3/2017

-- select * from #tmp where IsConverted = 0
--LEFT TABLE
ID  Name  IsConverted  Coverage
2   abc   0            Test1
3   abc   0            Auto
4   xyz   0            Home

-- select * from #tmp where IsConverted = 1
--RIGHT TABLE
ID  Name  IsConverted  Coverage
1   abc   1            Test1

-- DESIRED RESULTS
ID  Name  IsConverted  Coverage
1   abc   1            Test1
2   abc   0            Test1

-- CURRENT RESULTS
ID  Name  IsConverted  Coverage
2   abc   0            Test1



select *
from 
    (SELECT * FROM #tmp tmp WHERE tmp.IsConverted = 0) nc
join
    (SELECT * FROM #tmp tmp WHERE tmp.IsConverted = 1) ic on ic.Name = nc.Name and ic.Coverage = nc.Coverage

I need to be able to get the matching records from both tables, left and right. The reason for this is very complicated and does not add any additional information for this post.

I have tried FULL OUTER JOIN, CROSS APPLY, OUTER APPLY. Nothing is working.

EDIT:

Preferably I would like to use JOIN because once I find the matching results, I still need access to the left table and the right table because I need to make sure the LEFT.EarliestPolicyEffectiveDate within 15 days of RIGHT.EarliestPolicyEffectiveDate .

I'm not sure I can do that if I do UNION ALL.

Like below example:

select *
from 
    (SELECT * FROM #tmp tmp WHERE tmp.IsConverted = 0) nc
join
    (SELECT * FROM #tmp tmp WHERE tmp.IsConverted = 1) ic on ic.Name = nc.Name and ic.Coverage = nc.Coverage
where 
    nc.EarliestPolicyEffectiveDate between DATEADD(d, -15, ic.EarliestPolicyEffectiveDate) and DATEADD(d, 15, ic.EarliestPolicyEffectiveDate)

Answer 1

I think there are better ways to do this, but UNION ALL and EXISTS seems to work here:

SELECT *
FROM #tmp t
WHERE IsConverted = 1 
AND EXISTS(SELECT 1 FROM #tmp
           WHERE IsConverted = 0
           AND Name = t.Name
           AND Coverage = t.Coverage)
UNION ALL
SELECT *
FROM #tmp t
WHERE IsConverted = 0
AND EXISTS(SELECT 1 FROM #tmp
           WHERE IsConverted = 1
           AND Name = t.Name
           AND Coverage = t.Coverage);

Answer 2

This works for me. have a subquery to get all the matching names between LEFT and RIGHT. and a subquery to get all matching coverage between LEFT AND RIGHT. then use 'AND' to link them together in the WHERE clause

select * from #tmp
where name in (Select LEF.Name from LEF 
                INNER JOIN RIG ON LEF.NAME = RIG.NAME) 
        and coverage in (Select LEF.coverage from LEF 
                INNER JOIN RIG ON LEF.coverage = RIG.coverage)

result:

ID          NAME       IsConverted Coverage   EarliestPolicyEffectiveDate
----------- ---------- ----------- ---------- ---------------------------
1           abc        1           Test1      2017-09-01
2           abc        0           Test1      2017-09-02

Answer 3

I think I see now that you are trying to join the LEFT TABLE directly to the RIGHT TABLE, not using #tmp as a middle join.

You need to UNION the two where they intersect.

Psuedocode:

SELECT * FROM LEFT TABLE WHERE EXISTS(matching row in RIGHT TABLE)
UNION 
SELECT * FROM RIGHT TABLE WHERE EXISTS(matching row in LEFT TABLE)