所有联接均满足条件的SQL连接

Question

I need a little help for an SQL query.

I have tables: clients | claims | statuses | contacts

I have a query to find all clients and their contact details where any of their claims is a specified status:

SELECT
  clients.id           AS "Client Ref"
 ,claims.clientclaimid AS "Claim Number"
 ,Contacts.PhoneHome   AS "Mobile"
 ,statuses.description AS Status
FROM
  dbo.claims
LEFT JOIN
  statuses
    ON
    dbo.claims.statusID = statuses.ID
LEFT JOIN
  clients
    ON
    dbo.claims.clientid = clients.id
LEFT JOIN
  contacts
    ON
    clients.contactid = Contacts.id
WHERE
  statuses.description = 'client - pack sent to customer'
  AND (DATEADD(MM, -@joinedpremonthsago, GETDATE()) > clients.DateJoined)
  AND clients.DateJoined > 01 / 01 / 2012
  AND claims.active = 1
ORDER BY
  [Client Ref]
 ,[Claim Number];

I now need this to only pull clients where ALL of their claims are in specified status, but I don't know how to do this. How can I get clients where all of the claims have this status description? Could I have guidance or solutions for this?

Here is relevant schema; Claims Table

Contacts Table

Clients Table

Here is an image of the query returning where ANY of the client's claims are in status; Current results

Answer 1

The solution is to use the principle of exclusion. You write a query to get all clients that do have the status at least once. Great news: that part is already done :) Next you write a query to find clients that have any other status. Once you have both queries, you put them together to exclude the 2nd set from the first. You can do this in several ways: a NOT EXISTS() expression, a NOT IN() expression, an exclusion join, or the EXCEPT keyword can all work.

Personally I'm most comfortable with exclusion joins, but NOT EXISTS() is more common and tends to perform a little better:

select cli.id as "Client Ref", cla.clientclaimid as "Claim Number", co.PhoneHome as "Mobile"

from dbo.claims cla

inner join statuses s on cla.statusID = s.ID 
inner join clients cli on cla.clientid = cli.id
left join contacts co on cli.contactid = co.id

where s.description = 'client - pack sent to customer'
    and (DateAdd(MM, -@joinedpremonthsago, GetDate()) >  cli.DateJoined) 
    and cli.DateJoined > 01/01/2012
    and cla.active=1

    and NOT EXISTS ( 
        select 1 
        from clients cli0
        inner join claims cla0 on cla0.clientid = cli0.id
        inner join statuses s0 on s0.ID = cla0.statusID
        WHERE cli0.ID = cli.ID
           AND s0.description <> 'client - pack sent to customer'
    )

order by [Client Ref], [Claim Number]

Exclusion join version:

select cli.id as "Client Ref", cla.clientclaimid as "Claim Number", co.PhoneHome as "Mobile"

from dbo.claims cla

inner join statuses s on cla.statusID = s.ID AND s.description = 'client - pack sent to customer'
inner join clients cli on cla.clientid = cli.id
left join contacts co on cli.contactid = co.id
-- the "JOIN" part of an exclusion join
left join statuses s2 on cla.statusID = s2.ID AND s2.description <> 'client - pack sent to customer'

where (DateAdd(MM, -@joinedpremonthsago, GetDate()) >  cli.DateJoined) 
    and cli.DateJoined > 01/01/2012
    and cla.active=1

    -- the "EXCLUSION" part of an exclusion join
    and s2.ID IS NULL

order by [Client Ref], [Claim Number]

Note how I chose inner rather then left for some of the original joins. The way fields from those tables were used in the WHERE clause already made them effectively inner joins. Being honest about the join type helps you spot bugs and may allow Sql Server to build a better execution plan.

Also note I removed the status from the SELECT clause results, as that is now implied by the requirements.

Finally, note how I added table aliases to the query. It's good practice to always use table aliases with your queries. It's absolutely necessary to avoid ambiguity if you want to reference the same table more than once in a single query, as we do in both examples here. By convention, these aliases are often short — even single letter — mnemonics for the table names. So cli in this query is short for client , and I used 3 whole characters so it can be distinguished from claims . cli0 is used in the inner query to mean "client prime"... think of it as if the 0 were a subscript.

Answer 2

Something like (totaly untested code!):

select  clients.id as "Client Ref", claims.clientclaimid as "Claim Number",
        Contacts.PhoneHome as "Mobile",statuses.description as Status
from dbo.claims
left join clients on dbo.claims.clientid = clients.id
left join contacts on clients.contactid = contacts.id

where (DateAdd(MM, -@joinedpremonthsago, GetDate()) >  clients.DateJoined) 
    and clients.DateJoined > 01/01/2012
    and claims.active=1
    and dbo.claims.clientID in (
       select dbo.claims.clientID 
       from dbo.claims
       left join statuses on dbo.claims.statusID = statuses.ID
       where statuses.description = 'client - pack sent to customer'
    )

order by [Client Ref], [Claim Number]

Should do the trick.