Description:
------------
pg_insert() does not accept empty lists of values. Empty lists of values can be useful for tables with defaults set on columns. Postgres provides a construct for inserting an empty list: "INSERT INTO foo DEFAULT VALUES".

Reproduce code:
---------------
pg_query($conn, 'CREATE TABLE foo (id SERIAL PRIMARY KEY, time TIMESTAMP NOT NULL DEFAULT now())');
var_dump( pg_insert($conn, 'foo', array('time' => '2007-08-08 1:30:00'), PGSQL_DML_STRING));
var_dump( pg_insert($conn, 'foo', array(), PGSQL_DML_STRING));


Expected result:
----------------
string(53) "INSERT INTO foo (time) VALUES ('2007-08-08 1:30:00');"
string(30) "INSERT INTO foo DEFAULT VALUES"

Actual result:
--------------
string(53) "INSERT INTO foo (time) VALUES ('2007-08-08 1:30:00');"
bool(false)