You might need to add explicit type casts.

 I have a table running on Linux\Postgresql 8.3.4:

 CREATE TABLE "public"."active_sessions" (
   "id" VARCHAR(11) DEFAULT nextval('id_seq'::regclass) NOT NULL,
   "browser_type" VARCHAR(100),
   "session_id" VARCHAR(50),
   "ip_address" INET,
   "username" VARCHAR(50),
   "access_time" TIMESTAMP WITHOUT TIME ZONE,
   "user_rand" VARCHAR(15),
   "user_activity" TIMESTAMP WITHOUT TIME ZONE,
   CONSTRAINT "active_sessions_pkey" PRIMARY KEY("id")
 ) WITHOUT OIDS;

 I can insert the TIMESTAMP('s) into this table without issue but when I
 update the new entry the following error is received:

 ERROR:  operator does not exist: character varying = integer at character
 75
 HINT:  No operator matches the given name and argument type(s). You might
 need to add explicit type casts.
 STATEMENT:  UPDATE active_sessions SET access_time = '12/28/2008 8:51:33
 PM' WHERE id = 469

 I have read several archives describing the 8.3 release notes and CASTing
 but I do not understand how to apply this information, this issue makes no
 sense. Insert = ok, Update = "BOOM!".

 I have tried this statement with CURRENT_TIMESTAMP, now() but neither
 works.

 This statement is created using PHP 5.2.6 on a Linux server using PDO and
 prepared statements

 Any help with this issue is appreciated.

 Thanks in advance,
 Kulmacet