[SQL] SQL question

[Carolyn Lu Wong]

I have table with the following definition:

        create table table1(
                account_no      int4,
                start_date_tme  datetime
                ....
        );

The table may contain null values for start_date_time.

When I run the following SQL query, it fails:

        select * from table1
        where start_date_time::date >= '01/01/2000'::date 
        and start_date_time::date <= '01/01/2001'::date;

I get error message 'Unable to convert null datetime to date.

It's fine if I run the same SQL query with added condition as follows:

        select * from table1
>       where account_no = 1
        and start_date_time::date >= '01/01/2000'::date 
        and start_date_time::date <= '01/01/2001'::date;

Is this a bug? Or there's an logical explaination for this?