ben.norris (10/30/2012)
It doesn't state that the field is nullable
First: It does. The CREATE TABLE script does not include a NOT NULL constraint, so the columns are all nullable.
Second: That is irrelevant. Even when the column is not nullable, operating a LEAD function on it can still result in NULL values. So every column in a result set that is calculated using LEAD will always be nullable, and that does not have to be explicitly stated.