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

static void
exit_nicely(PGconn *conn)
{
	PQfinish(conn);
	exit(1);
}

int
main(int argc, char **argv)
{
	const char *conninfo;
	PGconn	   *conn;
	PGresult   *res;

	if (argc > 1)
		conninfo = argv[1];
	else
		conninfo = "dbname = postgres user = postgres";

	/* Make a connection to the database */
	conn = PQconnectdb(conninfo);

	/* Check to see that the backend connection was successfully made */
	if (PQstatus(conn) != CONNECTION_OK)
	{
		fprintf(stderr, "Connection to database failed: %s",
				PQerrorMessage(conn));
		exit_nicely(conn);
	}

	printf("Initial PQtransactionStatus: %d\n",
		   PQtransactionStatus(conn));

	res = PQexec(conn, "BEGIN");
	if (PQresultStatus(res) != PGRES_COMMAND_OK)
	{
		fprintf(stderr, "BEGIN failed: %s", PQerrorMessage(conn));
		PQclear(res);
		exit_nicely(conn);
	}
	PQclear(res);

	printf("PQtransactionStatus after BEGIN: %d\n",
		   PQtransactionStatus(conn));

	res = PQexec(conn, "COMMIT");
	if (PQresultStatus(res) != PGRES_COMMAND_OK)
	{
		fprintf(stderr, "COMMIT failed: %s", PQerrorMessage(conn));
		PQclear(res);
		exit_nicely(conn);
	}
	PQclear(res);

	printf("PQtransactionStatus after COMMIT: %d\n",
		   PQtransactionStatus(conn));

	res = PQexec(conn, "BEGIN; COMMIT");
	if (PQresultStatus(res) != PGRES_COMMAND_OK)
	{
		fprintf(stderr, "BEGIN; COMMIT failed: %s", PQerrorMessage(conn));
		PQclear(res);
		exit_nicely(conn);
	}
	PQclear(res);

	printf("PQtransactionStatus after BEGIN; COMMIT: %d\n",
		   PQtransactionStatus(conn));

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

	return 0;
}