(PHP 4 >= 4.2.0, PHP 5)
pg_field_type — Returns the type name for the corresponding field number
$result
   , int $field_number
   )
   pg_field_type() returns a string containing the
   base type name of the given field_number in the
   given PostgreSQL result resource.
  
Note:
If the field uses a PostgreSQL domain (rather than a basic type), it is the name of the domain's underlying type that is returned, rather than the name of the domain itself.
Note:
This function used to be called pg_fieldtype().
result
     PostgreSQL query result resource, returned by pg_query(), pg_query_params() or pg_execute() (among others).
field_number
      Field number, starting from 0.
   A string containing the base name of the field's type, or FALSE
   on error.
  
Example #1 Getting information about fields
<?php
  $dbconn = pg_connect("dbname=publisher") or die("Could not connect");
  // Assume 'title' is a varchar type
  $res = pg_query($dbconn, "select title from authors where author = 'Orwell'");
  echo "Title field type: ", pg_field_type($res, 0);
?>
The above example will output:
Title field type: varchar