void
PostgresMain(int argc, char *argv[], const char *dbname, const char *username)
{
	/*
	 * Non-error queries loop here.
	 */

	for (;;)
	{
	  // read a command
	  firstchar = ReadCommand(&input_message);
	  switch (firstchar)
		{
			case 'Q': /* simple query */
			{
         exec_simple_query(query_string);
       }
	}
}