#include <stdio.h>
#include <pgsql/libpq-fe.h>

int main() {
    PGconn *conn;
    PGresult *res;
    int rec_count;
    int row;
    int col;

    //Creating a connection to database
    conn = PQconnectdb("dbname=riverdata host=ewis.pld.ttu.ee user=student password=iag0582");

    //Check connection status
    if (PQstatus(conn) == CONNECTION_BAD) {
        printf("We were unable to connect to the database\n");
        return 0;
    }

    //Execute query
    //res = PQexec(conn, "SELECT name, length_km FROM river LIMIT 10;");
    //res = PQexec(conn, "SELECT id_river, name, length_km FROM river ORDER BY length_km DESC LIMIT 5;");
    res = PQexec(conn, "SELECT id_river, name, length_km FROM river WHERE id_river=id_mainriver AND length_km >70;");

    //Check query result status
    if (PQresultStatus(res) != PGRES_TUPLES_OK) {
        printf("We did not get any data!\n");
        PQfinish(conn);
        return 0;
    }

    //records count
    rec_count = PQntuples(res);

    printf("We received %d records.\n", rec_count);

    printf("==========================\n");

    //Print received records
    for (row=0; row<rec_count; row++) {
        for (col=0; col<3; col++) {
            printf("%-10s\t", PQgetvalue(res, row, col));
        }
        printf("\n");
    }

    printf("==========================\n");

    //Free PGresult handle
    PQclear(res);

    //Close the connection and free the memory used by PGconn handler
    PQfinish(conn);

    return 0;
}