How to store NULL values in datetime fields in MySQL?

Question

I have a \"bill_date\" field that I want to be blank (NULL) until it\'s been billed, at which point the date will be entered.

I see that MySQL does not like NULL val

Answer 1

It depends on how you declare your table. NULL would not be allowed in:

create table MyTable (col1 datetime NOT NULL);

But it would be allowed in:

create table MyTable (col1 datetime NULL);

The second is the default, so someone must've actively decided that the column should not be nullable.