postgresql empty date field

[pioppiop]

Operating system :linux debian
postgreSQL 7.1
PHP 4

I have read all article on empty date field
but i can't get it to work.
here is my query that use :

$result = pg_exec($connect_base,"UPDATE \"TCNC\" SET \"Date\"= '$date_1',\"Etabli par\"='$etabli_par' WHERE \"N_CNC\"='$num_cnc'
Note that $date_1 is equal to ""
i tried NULL,\N... but it does not work

and it tell me:
Warning: PostgreSQL query failed: ERROR: Bad date external representation 'null'

Can you help me please
Sorry if my english is not correct
( i'm french)

Thank you in advance
Franky

[[deleted]]

NULL is not a string, it's an SQL keyword.

Either insert nothing (quotes with nothing between them) or insert literally NULL.
Make sure you don't quote NULL in your query:

INSERT INTO table (date_field) VALUES (NULL);
INSERT INTO table (date_field) VALUES ("");

Bad:

INSERT INTO table (date_field) VALUES ('NULL');