On 20/03/08 14:31, Jaime Carrera wrote:
Hi Markus and Moritz,
Thanks for your suggestions; I tried another loop (the one from v.in.db)
and gave the result that I needed. Below are my "experiments":
The first db_fetch loop (exits after one interaction): I have to "cheat"
to be able to get all the records from the database:
while(1){
if(db_fetch (&cursor, DB_NEXT, &more) != DB_OK)
return(-1);
nodeprop=db_get_value_as_double(dbvalue,ctype);
printf("node prop= %.2f\n",nodeprop);
count++;
if(count<12699) /* use max(cat) value for this one, just testing*/
more=0;
if ( more) break;
}
Now, using the loop as used in v.in.db I get what I need, without
"cheating':
while ( db_fetch (&cursor, DB_NEXT, &more ) == DB_OK && more ) {
nodeprop=db_get_value_as_double(dbvalue,ctype);
printf("node prop= %.2f\n",nodeprop);
}
There are two differences: on the first loop more==1 immediately, and
thus exits the loop; while on the second one the loop is exptecting
more==1. Another difference is the != or == DB_OK part.
What I can gather from this, is that the first loop is more appropriate
to queries done on a category basis, but not for fetching an entire table.
I don't really understand the first one. Why do you break if more==1 ?
Instead of
if(count<12699) /* use max(cat) value for this one, just testing*/
more=0;
if ( more) break;
Shouldn't this just be
if(!more) break;
?
Moritz
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