/* testpg.c
   Test der PostgreSQL C Bibliothek

   Der Quellcode ist aus dem alten Postgres95 Handbuch
   
   Matthias Teege, 7. November 1999
*/
#include <stdio.h>
#include "libpq-fe.h"
/* #include "/usr/local/pgsql/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 og 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 (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 instances from the pg_database, the system catalog of
           database */
    res = PQexec(conn,"DECLARE myportal CURSOR FOR select * from pg_database");
    if (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 myportal");
    if (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 attributes names */
    nFields = PQnfields(res);
    for (i=0; i < nFields; i++) {
        printf("%-15s",PQfname(res,i));
    }
    printf("\n");

        /* next, print out the instances */
    for (i=0; i < PQntuples(res); i++) {
        for (j=0; j < nFields; j++) {
            printf("%-15s", PQgetvalues(res,i,j));
        }
        printf("\n");
    }

    PQclear(res);

        /* close the portal */
    res = PQexec(conn, "CLOSE myportal");
    PQclear(res);

        /* end the transaction */
    res = PQexec(conn, "END");
    PQclear(res);

        /* close the connection to the database and cleanup */
    PQfinish(conn);
        /* fclose(debug); */
}