Thread: coalesce a null to a char ?

coalesce a null to a char ?

From
"Gauthier, Dave"
Date:

How can I do this....

 

selcet coalesce((select ‘y’ from foo where name = f.name),’n’) from foo f where...

 

So the query returns a “y” or “n” depending on whether or not the subquery is null.

 

I get...

 

“ERROR: failed to find conversion function from unknown to text”

 

 

Re: coalesce a null to a char ?

From
Raymond O'Donnell
Date:
On 06/04/2009 22:55, Gauthier, Dave wrote:
> How can I do this....
>
> selcet coalesce((select 'y' from foo where name = f.name),'n') from foo f where...
>
> So the query returns a "y" or "n" depending on whether or not the subquery is null.

Are you sure that the subquery is returning any rows? Try something like
this instead (not tested):

  select
    case
      when exists(select 1 from foo where name = f.name) then 'y'
      else 'n'
    end
  from foo....

Ray.

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Raymond O'Donnell, Director of Music, Galway Cathedral, Ireland
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