#include <stdlib.h>
#include <libpq-fe.h>

void printTuples(PGresult *result) {
   int n = 0, r = 0;
   int nrows   = PQntuples(result);
   int nfields = PQnfields(result);
   printf("number of rows returned = %d\n", nrows);
   printf("number of fields returned = %d\n", nfields);
   for(r = 0; r < nrows; r++) {
     for(n = 0; n < nfields; n++)
       printf(" %s = %s", PQfname(result, n), PQgetvalue(result,r,n), PQgetlength(result,r,n));
     printf("\n");
   }
}



void doSQL(PGconn *conn, char *command){
  PGresult *result;
  printf("------------------------------\n");
  printf("%s\n", command);
  result = PQexec(conn, command);
  printf("status is : %s\n", PQresStatus(PQresultStatus(result)));
  printf("#rows affected: %s\n", PQcmdTuples(result));
  printf("result message: %s\n", PQresultErrorMessage(result));
  switch(PQresultStatus(result)) {
    case PGRES_TUPLES_OK:printTuples(result);
        break;
  }/* end switch */
  PQclear(result);
}

int main(){
  PGresult *result;
  PGconn *conn;
  int nTuples = 0;
  const char *connection_str = "host=localhost port=5432 dbname=*** user=***  password=***";
  conn = PQconnectdb(connection_str);
  if (PQstatus(conn) == CONNECTION_BAD) {
     fprintf(stderr, "Connection to %s failed, %s", connection_str, PQerrorMessage(conn));
  } else {
     printf("Connected OK\n");
     doSQL(conn, "BEGIN work");
     doSQL(conn, "DECLARE mcursor CURSOR FOR SELECT * FROM lab10.person");
     do {
       result = PQexec(conn, "FETCH 1 IN mcursor");
       if ( PQresultStatus(result) == PGRES_TUPLES_OK) {
          nTuples = PQntuples(result);
          printTuples(result);
          PQclear(result);
       } else nTuples = 0;
     } while (nTuples) ;
     doSQL(conn, "CLOSE mcursor");
     doSQL(conn, "COMMIT work");
  }
  // else
  // printf("connection failed: %s\n", PQerrorMessage(conn));
  PQfinish(conn);
  return EXIT_SUCCESS;
}