How Can I assign a sequence value to a sqlite field when the field UID value is NULL

Question

How I can assign a sequence value to a field "UID" which is NUll in existing sqlite table, for example

table: FOO  
name    UID
A   1
B   2
C   100
D   NULL
E   NULL
F   NULL

what I want is

table: FOO  
name    UID
A   1
B   2
C   100
D   101
E   102
F   103

Can some body help? I want to seek an alternative for using autoincrement on my own reason...

thanks!

Answer 1

Register a function that returns the number of times it's called, and then do

UPDATE FOO SET UID = 100 + increment() WHERE UID IS NULL

Answer 2

a drafted approach in my mind, I have no idea if it works fine and how much it reliable......

CREATE TRIGGER auto_next_id
AFTER INSERT ON table FOR EACH ROW
BEGIN
   UPDATE table SET uid = max(uid) + 1 ;
END;