ORDER BY ROW_NUMBER

Question

UPD: thanks for all, topic closed, after sleeping I understand everything =)

I have a problem with understanding OVER clause and and ROW_NUMBER function. Simple tabl

Answer 1

You can't ORDER BY the ROW_NUMBER directly: I don't know why you didn't get an error on this case, but normally you would. Hence the use of derived tables or CTEs

SELECT
    name, number
FROM
    (
    SELECT
       name,
       ROW_NUMBER() OVER (PARTITION BY name ORDER BY name) as number,
       AVG(mark) OVER (PARTITION BY name) AS nameavg
    FROM table
    ) foo
ORDER BY
   nameavg, number

However, PARTITION BY name ORDER BY name is meaningless. Each partition has random order because the sort is the partition

I suspect you want something like this where ROW_NUMBER is based on AVG

SELECT
    name, number
FROM
    (
    SELECT
       name,
       ROW_NUMBER() OVER (PARTITION BY name ORDER BY nameavg) AS number
    FROM
        (
        SELECT
           name,
           AVG(mark) OVER (PARTITION BY name) AS nameavg
        FROM table
        ) foo
    ) bar
ORDER BY
    number

Or more traditionally (but name is collapsed for the average)

SELECT
    name, number
FROM
    (
    SELECT
       name,
       ROW_NUMBER() OVER (PARTITION BY name ORDER BY nameavg) AS number
    FROM
        (
        SELECT
           name,
           AVG(mark) AS nameavg
        FROM
           table
        GROUP BY
           name
        ) foo
    ) bar
ORDER BY
    number

You can maybe collapse the derived foo and bar into one with

ROW_NUMBER() OVER (PARTITION BY name ORDER BY AVG(mark))

But none of this makes sense: I understand that your question is abstract about how it works bit it is unclear question. It would make more sense if you described what you want in plain English and with sample input and output