(PHP 4 >= 4.2.0, PHP 5, PHP 7)
pg_last_oid — Returns the last row's OID
$result
   ) : stringpg_last_oid() is used to retrieve the OID assigned to an inserted row.
OID field became an optional field from PostgreSQL 7.2 and will not be present by default in PostgreSQL 8.1. When the OID field is not present in a table, the programmer must use pg_result_status() to check for successful insertion.
   To get the value of a SERIAL field in an inserted
   row, it is necessary to use the PostgreSQL CURRVAL
   function, naming the sequence whose last value is required.  If the
   name of the sequence is unknown, the pg_get_serial_sequence
   PostgreSQL 8.0 function is necessary.
  
   PostgreSQL 8.1 has a function LASTVAL that returns
   the value of the most recently used sequence in the session.  This avoids
   the need for naming the sequence, table or column altogether.
  
Note:
This function used to be called pg_getlastoid().
resultPostgreSQL query result resource, returned by pg_query(), pg_query_params() or pg_execute() (among others).
   A string containing the OID assigned to the most recently inserted
   row in the specified connection, or FALSE on error or
   no available OID.
  
Example #1 pg_last_oid() example
<?php
  // Connect to the database
  pg_connect("dbname=mark host=localhost");
  // Create a sample table
  pg_query("CREATE TABLE test (a INTEGER) WITH OIDS");
  // Insert some data into it
  $res = pg_query("INSERT INTO test VALUES (1)");
  $oid = pg_last_oid($res);
?>