DEFAULT now() ?

May someone please show me the necessary code snippets that would allow the value of a column to take the current time ( ala now() ) by default on INSERT?

 

Indicative example:

 

CREATE TABLE foo (

    a INTEGER NOT NULL DEFAULT 0,

    b DATETIME NOT NULL DEFAULT now()

);

 

INSERT INTO foo (a) VALUES (123);

 

What happens here? Well, a row is inserted into table ``foo'' where ``a'' has the value 123 and b holds the date & time of when the create DDL statement was executed. I'm wondering how to get b to have the value of the time whenever any arbitrary insert statement is executed...

 

Ty