Обсуждение: math problem

Hello All,


I need to find a workaround for my addition problem.

I have a list of values in 3 columns derived from a  left join
where the last column is the sum of the 2 on the left.

i.e.

select cola, colb, sum(cola + colb) from ....

cola  colb total
2     3    5
2     2    4





now my problem comes into play when one of the
columns is empty. I always get a NULL or empty total.
this makes sence since NULL + 5 does not produce anything.


cola colb total

      3
1
4

etc.



Any work around for this, do I have to use a
Pg language? I guess I could write a script in perl
to take of this for me but I would like to tap
the brains here to see it can al be done in the
SQL.
Thanks








--
Vincent Stoessel
Linux Systems Developer
vincent xaymaca.com

On Thu, 25 Jul 2002, Vincent Stoessel wrote:

> cola colb total
>
>       3
> 1
> 4
>
> etc.
>
>
>
> Any work around for this, do I have to use a
> Pg language? I guess I could write a script in perl
> to take of this for me but I would like to tap
> the brains here to see it can al be done in the
> SQL.

If you're trying to get 3, 1, and 4 respectively,
you might want:
coalesce(cola,0)+coalesce(colb,0)

On Thu, 25 Jul 2002, Vincent Stoessel wrote:

> now my problem comes into play when one of the
> columns is empty. I always get a NULL or empty total.
> this makes sence since NULL + 5 does not produce anything.

I think colesce is your friend

select cola, colb, sum(colesce(cola,0) + colesce(colb,0)) from ....

I've never had to use it put I've seen this situation addressed here
before.   Table 9.3, pg 113 the Elephant book.


Rod
--
  "Open Source Software - Sometimes you get more than you paid for..."

Thank You all for the answer.
I appreciate it a lot. For the record the function is spelled
coalesce.
Later


Roderick A. Anderson wrote:
> On Thu, 25 Jul 2002, Vincent Stoessel wrote:
>
>
>>now my problem comes into play when one of the
>>columns is empty. I always get a NULL or empty total.
>>this makes sence since NULL + 5 does not produce anything.
>
>
> I think colesce is your friend
>
> select cola, colb, sum(colesce(cola,0) + colesce(colb,0)) from ....
>
> I've never had to use it put I've seen this situation addressed here
> before.   Table 9.3, pg 113 the Elephant book.
>
>
> Rod


--
Vincent Stoessel
Linux Systems Developer
vincent xaymaca.com

On Fri, 26 Jul 2002, Vincent Stoessel wrote:

> Thank You all for the answer.
> I appreciate it a lot. For the record the function is spelled
> coalesce.

Now how did I do that?  Ah, old eyes, and cut and paste.  Type once, copy
wrong spelling many times.


Rod
--
  "Open Source Software - Sometimes you get more than you paid for..."