Re: [SQL] DISTINCT count(*), possible?

Out of curiosity, more than anything else.
Would the group by solve this problem?

Rudy

On 16 Jun 99, at 10:24, Tom Lane wrote:

> Another way is
>
> SELECT DISTINCT field INTO temp_table FROM mytable;
> SELECT count(*) FROM temp_table;
> DROP TABLE temp_table;
>
> which is arguably more efficient than the previous solution
> for large tables --- it should involve O(n log n) work rather
> than O(n^2). For a small table, the overhead of creating and
> dropping a table might overshadow the actual work, though.
>
> In 6.5 you can use "INTO TEMP temp_table" and avoid worrying
> about having to invent distinct temp table names for concurrent
> users of the database.
>
> The SQL-standard "SELECT count(DISTINCT field)" would be even nicer,
> of course, but I dunno when someone will get around to it...
>
> regards, tom lane
>
>