(PHP 4 >= 4.2.0, PHP 5)
pg_result_error — Get error message associated with result
$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.
  
resultPostgreSQL query result resource, returned by pg_query(), pg_query_params() or pg_execute() (among others).
   Returns a string. Returns empty string if there is no error. If there is an error associated with the
   result parameter, returns FALSE.
  
Example #1 pg_result_error() example
<?php
  $dbconn = pg_connect("dbname=publisher") or die("Could not connect");
  if (!pg_connection_busy($dbconn)) {
      pg_send_query($dbconn, "select * from doesnotexist;");
  }
  
  $res1 = pg_get_result($dbconn);
  echo pg_result_error($res1);
?>