Search and replace ID query with a twist

Hi

I have a minor query issue I'm stuck with. I have a n-m table containing relations between contacts and lists.
I need to do a search and replace contact A with B in the table however I may only replace where the if B is not already in the list for a given Database ID.

E.g. Contact 14 must be replaced with Contact 16

Contact 14 exists in list 11, both in database 0 and 1
Contact 16 exists in list 11, in database 0

In this case it is straight forward to replace contact 14 in database 1, however doing that in database 0 would give 2 * 16 in that database which is not allowed. So in that case I must set the new contact to the highest priority (lowest number) of the two and remove the other one.

So the combined unique key is CallListID+ContactID+DatabaseID - priority is just a ranking of the list where priority 1 is the highest.

So if this is the staring point data set

CallListID  ContactID   Priority    DatabaseID
----------- ----------- ----------- -----------
11          3           1           1
11          7           2           1
11          9           3           1
11          14          4           1
11          7           1           0
11          16          2           0
11          14          3           0

The result should end like this

CallListID  ContactID   Priority    DatabaseID
----------- ----------- ----------- -----------
11          3           1           1
11          7           2           1
11          9           3           1
11          16          4           1
11          7           1           0
11          16          2           0

OR, if the starting point is this

CallListID  ContactID   Priority    DatabaseID
----------- ----------- ----------- -----------
11          3           1           1
11          7           2           1
11          9           3           1
11          14          4           1
11          7           1           0
11          14          2           0
11          16          3           0

it should result in this

CallListID  ContactID   Priority    DatabaseID
----------- ----------- ----------- -----------
11          3           1           1
11          7           2           1
11          9           3           1
11          16          4           1
11          7           1           0
11          16          2           0

CREATE TABLE [dbo].[CallLists_Contacts](
	[CallListID] [int] NOT NULL,
	[ContactID] [int] NOT NULL,
	[Priority] [int] NOT NULL,
	[DatabaseID] [int] NOT NULL
) ON [PRIMARY]

Here are some inserts

INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(3,2,1,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(3,2,1,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(4,2,1,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(4,2,1,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(5,2,1,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(5,2,1,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(6,2,1,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(6,2,1,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(7,3,1,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(7,3,1,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(8,2,1,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(8,2,1,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(9,2,1,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(9,3,2,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(9,16,3,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(9,2,1,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(9,3,2,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(9,16,3,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(10,3,1,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(10,16,2,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(11,3,1,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(10,3,1,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(11,7,2,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(11,9,3,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(11,14,4,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(11,7,1,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(15,3,1,1)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(15,3,1,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(11,16,2,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(10,16,3,0)
INSERT INTO [CallLists_Contacts] ([CallListID],[ContactID],[Priority],[DatabaseID])VALUES(11,14,3,0)

Does anyone know how to solve this in a query?

Henry