Cursor variable not updated - sql-server

Question

I'm not understanding why the variable, #NextURLId, in this cursor is not being updated. Here is the code
DECLARE #NextURLId INT = 1
DECLARE #varContact_Id INT
DECLARE GetURL_Cursor CURSOR FOR
SELECT DISTINCT(contact_id)
FROM obp.Contacts
OPEN GetURL_Cursor
FETCH NEXT FROM GetURL_Cursor INTO #varContact_id
WHILE ##FETCH_STATUS = 0
BEGIN
-- Available URLs have the used value as NULL. Used has value of 1.
SET #NextURLId = (SELECT MIN(id) FROM obp.URL WHERE used IS NULL)
UPDATE obp.Contacts SET URL = (
SELECT url from obp.URL WHERE id = #NextURLId)
UPDATE obp.URL SET
used = 1,
contact_id = #varContact_Id,
date = GETDATE()
WHERE id = #NextURLId
FETCH NEXT FROM GetURL_Cursor INTO #varContact_id
END;
CLOSE GetURL_Cursor
DEALLOCATE GetURL_Cursor
The code is supposed to retrieve a unique URL from a table (obp.URL), enter that URL in the Contacts table and then update the URL to indicated that the URL has been used. It seems to me that after the URL table is updated with 'used = 1' then the next iteration of the code should get a new URLId when I query for it.
However, when I run this code I get the same URL every time. No doubt I am missing something obvious but need some help to point it out.
As a side, if there is a set based solution for this, I'd be happy to hear it.
TIA

Answer 1

this
UPDATE obp.Contacts SET URL = (
SELECT url from obp.URL WHERE id = #NextURLId)
updates every row with the same. Add a proper WHERE clause like
WHERE contact_id=#varContact_id
About the requirement for this: I understand that you want to associate a Contact with a URL and that there is no logical rule for which with what. At first sight I would consider a match table the right way to do this. It feels better to me to put such associations into a seperate table, even if there is a strong belief in a 1:1-relationship between the two objects associated. obp.URL and obp.Contacts are dimensional tables (I assume/hope). Keeping the association in one different table requires one action if changes occur. In your model a change must be reflected in both those tables.
Here is an idea for such a table:
create table Contact_URL_match
(ID int identity (1,1)
,URL_id int not null unique
,contact_id int not null unique
,created datetime)
the unique constraints disallow insertion of the same URL or the same Contact_id twice. On each insert/update prior content is being checked for duplicates and if found the action is denied, thus uniqueness protected.
For manifesting new matches in a first large initial action try this (haven't tested, just an idea)
INSERT INTO
Contact_URL_match
(URL_id
,contact_id
,created)
SELECT
urls.id
,contacts.contact_id
,getdate()
FROM
(SELECT
DISTINCT(contact_id)
,ROW_NUMBER() over (ORDER BY contact_id asc) rn
FROM
obp.Contacts) contacts
INNER JOIN
(SELECT
id
,ROW_NUMBER() over (ORDER BY id) rn
FROM
obp.URL) urls
ON
contacts.rn=urls.rn
Within the subqueries this creates a row number in both the source tables based on the ORDER BY clauses. It then joins the resultsets of the subqueries by that rownumber which is an act of deliberate randomness. I hope you want that. The result of that join is inserted into the match table.
If later you want to manifest a single new association you could add WHERE clauses to the subqueries that specify what URL you want matched with what Contact. Before picking a URL or Contact check the match table with NOT EXISTS to make sure it is not used in there.
EDIT : syntax errors cleaned