Question

Let's say I have this table (this is simplified, of course there are other columns):

CompanyID (int)
ContactName (varchar(50))
ContactType (char(1))

with the values:

CompanyID | ContactName           | ContactType
-----------------------------------------------
1         | John Doe              |   A
1         | Jane Smith            |   B
2         | Ralph Jones           |   B
3         | Dick Grayson          |   A

What I want are all the companies where there's a ContactType='A', unless there is no ContactType='A' return the ContactType='B'. So in this example, I want:

1, John Doe (because he's a ContactType A)
2, Ralph Jones (because Company #2 doesn't have a ContactType A)
3, Dick Grayson (because he's a ContactType A)

I can't just say "A or B" because a company may have both.

Here's what I tried (and failed)

use MyFancyDatabase
drop table #TypeA
drop table #TypeB
drop table #TypeAB

create table #TypeA(ownerkey int, ContactName varchar(200), ContactType char(1))
insert #TypeA
Select ownerkey, ContactName, ContactType from address
where ContactType = 'A' and CancelDate is null

create table #TypeB(ownerkey int, ContactName varchar(200), ContactType char(1))
insert #TypeB
Select ownerkey, ContactName, ContactType from address
where ContactType = 'B' and CancelDate is null

create table #TypeAB(ownerkey int, ContactName varchar(200), ContactType char(1))
insert #TypeAB

select * from #TypeA
except
select * from #TypeB

I guess in English it's "A, but if there is no A, then take B."

Any suggestions?

Answer 1

I think this should work for you.

with SortedResults as
(
    select CompanyID
        , ContactName
        , ContactType
        , ROW_NUMBER() over (partition by CompanyID order by ContactType) as RowNum
    from ThisTable
)

select *
from SortedResults
where RowNum = 1

Answer 2

SELECT a.OwnerKey, a.CompanyName, Case WHEN a.ContactType IS NULL THEN b.ContactType ELSE a.ContactType END AS ContactType
FROM #TypeA a
LEFT JOIN #TypeB b on a.OwnerKey = b.OwnerKey

Answer 3

Try this SQL

Select t1.CompanyID , 
       ContactName =  IIF(t1.ContactType='A',t1.ContactName,t2.ContactName)
       ContactType =  IIF(t1.ContactType='A','A',t2.ContactType)
FROM address as t1 left join address as t2 
   on t1.CompanyID = t2.CompanyID 
     AND t1.ContactName = t2.ContactName
     AND (t1.ContactType <> t2.ContactType)

IF you have more type than A OR B and you want just A and B add this on the where statment

WHERE  (t1.ContactType = 'A' OR t1.ContactType = 'B')
   AND (t2.ContactType = 'A' OR t2.ContactType = 'B')

Answer 4

您定义的表格中的列似乎与示例查询中的列不匹配。我猜测OwnerKey与CompanyID相同吗？

如果是这样，并且保留了大部分代码，那么最后一次选择将需要：

select * from #TypeA
union all
select * from #TypeB
where not exists (
    select * 
    from #TypeA
    where #TypeA.ownerkey = #TypeB.ownerkey)

T-SQL return a row if another row doesn't exist

4 个答案: