Question

I have the need to find the next available number in a set:

select min([pivot])
from   [pivot]
where not exists (
      select null as nothing
      from   product
      where  product.id = [pivot].[pivot])

However, this app will be used for a very long time and the [pivot] field is an integer. I don’t really want to create 2,147,483,647 [pivot] records (sequential numbers from zero to a big number in a table). Creating a view takes too long.

Is there some function in T-SQL (Microsoft SQL Server 2005 / 2008) which can provide a [pivot] table without actually creating one. Creating a [pivot] view is bad because it takes a lot of time to access the view.

Answer 1

See if something like this will work for you. In my example, #Test has a hole at 5 that should be returned, the second (#Test2) has no holes, so we expect a new ID to be returned. It’s done by self-joining on itself. I’m not sure why you’ve got a pivot there, so I may be misunderstanding your problem.

CREATE TABLE #test
(
    num int
)

CREATE TABLE #test2
(
    num int
)

INSERT INTO #test (num)
SELECT 1 UNION ALL
SELECT 2 UNION ALL
SELECT 3 UNION ALL
SELECT 4 UNION ALL
SELECT 6 UNION ALL
SELECT 7 

INSERT INTO #test2 (num)
SELECT 1 UNION ALL
SELECT 2 UNION ALL
SELECT 3 UNION ALL
SELECT 4 UNION ALL
SELECT 5 UNION ALL
SELECT 6 UNION ALL 
SELECT 7

SELECT MIN(t1.num)+1 FROM #test t1
    LEFT JOIN #test t2 ON t1.num+1 = t2.num
    WHERE t2.num IS NULL

SELECT MIN(t1.num)+1 FROM #test2 t1
    LEFT JOIN #test2 t2 ON t1.num+1 = t2.num
    WHERE t2.num IS NULL