PostgreSQL/Date Timezone/timestamp

Using timestamp values correctly

postgres=#
postgres=# CREATE TABLE "shipments" (
postgres(#      "id" integer DEFAULT nextval(""shipments_ship_id_seq""::text) NOT NULL,
postgres(#      "customer_id" integer,
postgres(#      "isbn" text,
postgres(#      "ship_date" timestamp with time zone
postgres(# );
CREATE TABLE
postgres=#
postgres=# insert into shipments values (375,  142,  "039480001X","2004-01-06 09:19:21-01");
INSERT 0 1
postgres=# insert into shipments values (323,  671,  "0451160916","2004-02-14 10:26:41-02");
INSERT 0 1
postgres=# insert into shipments values (998,  1045, "0590445065","2004-03-12 12:39:47-03");
INSERT 0 1
postgres=#
postgres=#
postgres=# -- Using timestamp values correctly
postgres=#
postgres=# CREATE FUNCTION add_shipment (integer, text) RETURNS timestamp AS "
postgres"#   DECLARE
postgres"#      -- Declare aliases for function arguments.
postgres"#     customer_id ALIAS FOR $1;
postgres"#     isbn ALIAS FOR $2;
postgres"#
postgres"#     shipment_id INTEGER;
postgres"#     right_now timestamp;
postgres"#
postgres"#   BEGIN
postgres"#     right_now := ""now"";
postgres"#
postgres"#     SELECT INTO shipment_id id FROM shipments ORDER BY id DESC;
postgres"#
postgres"#     shipment_id := shipment_id + 1;
postgres"#
postgres"#     INSERT INTO shipments VALUES ( shipment_id, customer_id, isbn, right_now );
postgres"#
postgres"#     RETURN right_now;
postgres"#   END;
postgres"# " LANGUAGE "plpgsql";
CREATE FUNCTION
postgres=#
postgres=# select add_shipment(1, "123");
      add_shipment
-------------------------
 2006-10-18 19:15:49.125
(1 row)
postgres=#
postgres=# select * from shipments;
 id  | customer_id |    isbn    |         ship_date
-----+-------------+------------+----------------------------
 375 |         142 | 039480001X | 2004-01-06 02:19:21-08
 323 |         671 | 0451160916 | 2004-02-14 04:26:41-08
 998 |        1045 | 0590445065 | 2004-03-12 07:39:47-08
 999 |           1 | 123        | 2006-10-18 19:15:49.125-07
(4 rows)
postgres=#
postgres=# drop FUNCTION add_shipment (integer, text);
DROP FUNCTION
postgres=# drop table shipments;
DROP TABLE
postgres=#
postgres=#