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sqlsql-serveroraclegroup-bygreatest-n-per-group

SQL Server equivalent to Oracle's ANY_VALUE(...) KEEP (DENSE_RANK FIRST/LAST ORDER BY ...)

There's a technique in Oracle SQL that can be used to simplify aggregation queries.

Scenario: We've aggregated on a particular column — but we actually want to know information from a different column.

There are a number of ways to achieve that using SQL. I'm looking for a solution that lets me do it in a calculated column -- all within a single SELECT query (no subqueries, joins, WITH, etc.).

Like this:

--Oracle
--For a given country, what city has the highest population? (where the country has more than one city)
--Include the city name as a column.
select
    country,
    count(*),
    max(population),
    any_value(city)
        keep (dense_rank first order by population desc)
from
    cities
group by
    country
having
    count(*) > 1

db<>fiddle

As shown above, the following column can bring in the city name, even though the city name isn't in the GROUP BY:

 any_value(city) keep (dense_rank first order by population desc)

Is there equivalent functionality in SQL Server?

Related:

Edit:

I changed MAX() to ANY_VALUE(), since I think ANY_VALUE() is easier to read.

Ties can be broken by adding , city desc to the order by, making it deterministic:

any_value(city) keep (dense_rank first order by population desc, city desc)
Solution

  • SQL Server does not implement this.

    I'm looking for a solution that lets me do it in a calculated column -- all within a single SELECT query (no subqueries, joins, WITH, etc.)

    It's possible but not pretty (DB Fiddle).

    Assuming population is a positive integer then you could use the below (See Solution Based on Concatenation for the idea behind this approach)

    select
    country,
    count(*),
    max(population),
    SUBSTRING(MAX(FORMAT(population, 'D10') + city), 11, 8000)
from
    cities
group by
    country
having
    count(*) > 1