I have a C to postgres question.

From: "Jay G(dot) Scott" <gl(at)arlut(dot)utexas(dot)edu>
To: pgsql-novice(at)postgresql(dot)org
Subject: I have a C to postgres question.
Date: 2003-01-30 16:13:31
Message-ID: 200301301613.h0UGDVF27650@csdsun1.arlut.utexas.edu
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I'm hoping it's okay to post this kind of thing here. There's
no newsgroup, cruising the FAQs didn't turn up anything--or
I missed it.

The database has 4 values; I can see them when I get into the d.b.
via:
psql test
and, using (cut and paste) the string the C program uses to select,
from "psql test" I see the four values.
The string, I suppose, must be okay. Furthermore, if I turn on
tracing in the C program, I believe I see the four values being printed.
That makes me think the select statement syntax is correct.
However, my C program thinks it got 0 rows. And I can't retrieve anything.
So I think the problem is in my C code. I printed the online man
pages, it looks okay to me.
Here's the code fragment:
/*-----------------------------------------------*/
sprintf(select_stmt, "SELECT m_id FROM machines WHERE hostname = '%s'",
node);
fprintf(stderr,"trying this: %s\n", select_stmt);
/*____________________________________________________________________________*/
igot = PQsendQuery(conn_to_db,select_stmt);
fprintf(stderr,"igot from query is %d\n", igot );
seek_m_id = PQgetResult(conn_to_db);

estgot = PQresultStatus( seek_m_id );

fprintf(stderr,"estgot from PQgetResult is %d\n", estgot );

while( seek_m_id != NULL )
{
fprintf(stderr,"seek_m_id != NULL\n");
seek_m_id = PQgetResult(conn_to_db);
estgot = PQresultStatus( seek_m_id );
tmwh( estgot );
/* i suppose nrows could keep coming back as 1 */
nrows = PQntuples( seek_m_id );
fprintf(stderr,"nrows = %d\n", nrows );
for(jj=0;jj<nrows;jj++)
{
cgot = PQgetvalue( seek_m_id, jj, 0 );
machine_id = atoi( cgot );
fprintf(stderr,"machine_id = %d\n", machine_id );
}
PQclear(seek_m_id);
}
/*____________________________________________________________________________*/

--
Jay Scott 512-835-3553 gl(at)arlut(dot)utexas(dot)edu
Head of Sun Support, Sr. Operating Systems Specialist
Applied Research Labs, Computer Science Div. S224
University of Texas at Austin

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