SELECT COUNT(*)
FROM ( SELECT DISTINCT col1, col2.....
FROM ..........)
- Charu Joshi <joshic_at_mahindrabt.com> wrote:
> Thanks all,
>
> My question was related more to the 'design' of SQL language. To my
> mind the
> expression COUNT(DISTINCT a,b) looked a natural extension of the
> syntax
> COUNT(DISTINCT a). Even COUNT(DISTINCT(a,b)) would look good enough
> to me.
> Probably it's too trivial a thing to bother about. Using the
> subquery would
> very well give the desired results.
>
> I have been thinking of reading CJ Date and other experts' articles
> on the
> design (and limitations) of SQL, but couldn't find any good
> resources on the
> net. If you know of any links, then can you please let me know?
>
> Thanks once again,
> Charu.
>
> -----Original Message-----
> Sent: Wednesday, January 29, 2003 10:04 PM
> To: Multiple recipients of list ORACLE-L
>
> Charu,
> The COUNT() function requires a single expression. "ename, job" is
> not a valid expression. "ename||job" is a valid expression since it
> will
> return a single value.
> Another alternative would be
> select count(*)
> from (select distinct ename, job from emp);
>
> Dan Fink
>
> -----Original Message-----
> Sent: Wednesday, January 29, 2003 11:19 AM
> To: Multiple recipients of list ORACLE-L
>
> Hello Listers,
>
> How to find out the COUNT of DISTINCT values of multiple columns?
>
> For eg.
>
> SQL> SELECT DISTINCT ename FROM emp;
> -- This works.
>
> SQL> SELECT COUNT(DISTINCT ename) FROM emp;
> -- So does this.
>
> SQL> SELECT DISTINCT ename, job FROM emp;
> -- And this too.
>
> SQL> SELECT COUNT(DISTINCT ename, job) FROM emp;
> -- So why does this fail?
>
> I can do a COUNT(DISTINCT ename || job), but that doesn't seem to
> be elegant
> way of doing it.
>
> I have a feeling I might be missing some fairly basic syntax, but
> feeling
> dumb is better than suspense.
>
> Thanks & regards,
> Charu.
>
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> Author: Charu Joshi
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> Author: Charu Joshi
> INET: joshic_at_mahindrabt.com
>
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Sundeep Maini
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Currently on Assignement at Caterpillar Peoria
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Received on Thu Jan 30 2003 - 11:54:28 CST
