SELECT COUNT(*)
  FROM ( SELECT DISTINCT col1, col2.....
           FROM ..........)

--- Charu Joshi <[EMAIL PROTECTED]> 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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=====

Sundeep Maini 
Consultant 
Currently on Assignement at Caterpillar Peoria
[EMAIL PROTECTED] 

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