Description
string 
pg_result_error ( resource result )
   pg_result_error() returns any error message
   associated with the result resource. Therefore,
   the user has a better chance of getting the correct error message than
   with pg_last_error().
  
   The function pg_result_error_field() can give much greater
   detail on result errors than pg_result_error().
  
   Because pg_query() returns FALSE if the query fails,
   you must use pg_send_query() and
   pg_get_result() to get the result handle.