I’m trying to select the max id from any n number linked tuples in

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Asked: May 26, 20262026-05-26T04:24:01+00:00 2026-05-26T04:24:01+00:00

I’m trying to select the max id from any n number linked tuples in

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I’m trying to select the max id from any n number linked tuples in a sql server db – we are writing an upgrade script for some data sets within an app, and need to know what the highest upgrade available is based on what the data’s version is currently. For example, using the following simplified table ‘versions’:

oldVersionId   newVersionId
1              2
2              3
3              4
10             11

We know we are version 1, and want to get the highest version out there that we can upgrade to; which would return 4 in this case, and not 11. We can have 0-n number of upgradable versions available at any given time. I’m not an sql wiz, and could only think to query using a variable number of chained selects:

select newVersion from versions where oldVersionId = (select newVersion from versions where oldVersionId = 1)

But it not an n numbered search, and won’t return correctly if the number of elements is greater or less then the given. Is sql capable of performing such a query, and what elements / keywords should I be looking at to write one?

Solution:

You learn something new every day – I needed a hybrid of the two answers. Turns out sql can query a dataset using the tree-like child/parent linking that I’m way more comfortable with in OO languages.

In sql server you can set up a recursive tree walking call using a aliased table. You need an anchor and then the recursive bit. The first call is the anchor, I can use any value in the table, or a list of values, etc. The second select call just says to use the rest of the table to scan against.

Here is the syntax:

--Create the new alias (s)
;with s (oldVersionId, newVersionId) as 
(
    --set up the anchor node, 
    select oldVersionId, newVersionId from @t
    where oldVersionId = 1

    -- join it to the rest of the table, denoting that we only want nodes 
    -- where the old version is represented as a new version later
    union all
    select t.oldVersionId, t.newVersionId from @t as t
    inner join s on t.oldVersionId = s.newVersionId
)
--Return the max value from the nodes I collected
select max(s.newVersionId) from s