SQLite autoincrement field question

[ptbsG_Man]

Hello I was reading on sqlite.org about the way to make an autoincrement field and have done it and it works using the sqlite.exe and if i do "INSERT INTO t1 VALUES(NULL,123);" but in PHP if i try that the field that is set to INTEGER PRIMARY KEY is just blank so i tested there othere way "INSERT INTO t1 VALUES((SELECT max(a) FROM t1)+1,123);" and that works in PHP.

Now what i want to know is can INSERT INTO t1 VALUES(NULL, 123); work in PHP
ive tried

INSERT INTO t1 VALUES(NULL, 123);
and
INSERT INTO t1 VALUES('', 123);

thanks
-Don