Question

In standard SQL, is there a way to say:

select mubmle as x from mumblemmble

And get more than one line of results, like this

 x
 _ 
 1
 2
 3

without creating temporary tables? I can do it in SQL Server using row_count() if I know some table that has enough rows, like:

  select row_number() over (order by x.SomeColumn) from 
(select top 24 SomeColumn from TableThatHasAtLeast24Rows) x

But wonder if there’s a standard (less dumb) way to do it.

Answer 1

There is no standard way, and no way at all in MySQL.

In Oracle:

SELECT  *
FROM    dual
CONNECT BY
        level < n

In MS SQL:

WITH hier(row) AS
        (
        SELECT  1
        UNION ALL
        SELECT  row + 1
        FROM    hier
        WHERE   row < n
        )
SELECT  *
FROM    hier
OPTION (MAXRECURSION 0)

In PostgreSQL:

SELECT  *
FROM    generate_series (1, n)

Note that MS SQL, unlike Oracle, cannot swap recursion stack into temporary tablespace, so you may experience troubles when generating large datasets.

See this answer for more details