Hello All,
Im novice to Postgres ,Im trying to program in 'libpq the C
application programmer's interface to PostgreSQL'
I was trying to execute sample 'testlibpq.c'.
I did the following......
#su postgres(enter)
(bash#)createdb sampledb
(bash#)psql sampledb
(sampledb#)create table sirisha (name varchar(20),city varchar(20));
(sampledb#)insert into sirisha(name,city) values('Vikram','Toronto');
(sampledb#)\q
(bash#)gcc -I/usr/include/pgsql sirisha_retrieve.c -o output2 -lpq
(enter)
/usr/bin/ld: cannot open output file output2: Permission denied
collect2: ld returned 1 exit status
What does the above message signify? I tried to run the program as
root still the same prob ?
What is the problem?
Thanks in advance ......
Vikram.
*********Source Code is as follows.*********************
*
* testlibpq.c
*
* Test the C version of libpq, the PostgreSQL frontend
* library.
*/
#include <stdio.h>
#include <libpq-fe.h>
void
exit_nicely(PGconn *conn)
{
PQfinish(conn);
exit(1);
}
main()
{
char *pghost,
*pgport,
*pgoptions,
*pgtty;
char *dbName;
int nFields;
int i,
j;
/* FILE *debug; */
PGconn *conn;
PGresult *res;
/*
* begin, by setting the parameters for a backend connection if
the
* parameters are null, then the system will try to use
reasonable
* defaults by looking up environment variables or, failing that,
* using hardwired constants
*/
pghost = NULL; /* host name of the backend server */
pgport = NULL; /* port of the backend server */
pgoptions = NULL; /* special options to start up the
backend
* server */
pgtty = NULL; /* debugging tty for the backend
server */
dbName = "template1";
/* make a connection to the database */
conn = PQsetdb(pghost, pgport, pgoptions, pgtty, dbName);
/*
* check to see that the backend connection was successfully made
*/
if (PQstatus(conn) == CONNECTION_BAD)
{
fprintf(stderr, "Connection to database '%s' failed.\n",
dbName);
fprintf(stderr, "%s", PQerrorMessage(conn));
exit_nicely(conn);
}
/* debug = fopen("/tmp/trace.out","w"); */
/* PQtrace(conn, debug); */
/* start a transaction block */
res = PQexec(conn, "BEGIN");
if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "BEGIN command failed\n");
PQclear(res);
exit_nicely(conn);
}
/*
* should PQclear PGresult whenever it is no longer needed to
avoid
* memory leaks
*/
PQclear(res);
/*
* fetch rows from the pg_database, the system catalog of
* databases
*/
res = PQexec(conn, "DECLARE mycursor CURSOR FOR SELECT * FROM
pg_database");
if (!res || PQresultStatus(res) != PGRES_COMMAND_OK)
{
fprintf(stderr, "DECLARE CURSOR command failed\n");
PQclear(res);
exit_nicely(conn);
}
PQclear(res);
res = PQexec(conn, "FETCH ALL in mycursor");
if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
{
fprintf(stderr, "FETCH ALL command didn't return tuples
properly\n");
PQclear(res);
exit_nicely(conn);
}
/* first, print out the attribute names */
nFields = PQnfields(res);
for (i = 0; i < nFields; i++)
printf("%-15s", PQfname(res, i));
printf("\n\n");
/* next, print out the rows */
for (i = 0; i < PQntuples(res); i++)
{
for (j = 0; j < nFields; j++)
printf("%-15s", PQgetvalue(res, i, j));
printf("\n");
}
PQclear(res);
/* close the cursor */
res = PQexec(conn, "CLOSE mycursor");
PQclear(res);
/* commit the transaction */
res = PQexec(conn, "COMMIT");
PQclear(res);
/* close the connection to the database and cleanup */
PQfinish(conn);
/* fclose(debug); */
return 0;
}
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