Обсуждение: Nulls

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Nulls

От
Michael Davis
Дата:
I have a function:
void *nz(void *bp) {      text *new_text;      new_text = (text *) palloc(sizeof(text)+2);      memset((void *)
new_text,0, sizeof(text)+2);         strcpy(VARDATA(new_text), ":");      VARSIZE(new_text) = sizeof(text)+2;
return(void *)(new_text);}
 

I define the function in psql:

CREATE FUNCTION nz(text) RETURNS text AS
'/usr/src/pgsql/contrib/spi/psql_ext.so' LANGUAGE 'c';

I call the function:
select addressid, nz(state) from addresses where addressid = 3870;

If state is NULL, nz(state) still returns NULL!  How can I get my nz()
function to reflect something other than NULL?  The purpose behind this is
to have a concatenated string return a value even if any value is null.  For
example:

select addressid, nz(state) || nz(country) from addresses where addressid =
3870;

Returns NULL if state is null or if country is null.  I want it to return
the country if state is null.