I am getting exasperated.
I have a lot of experience with relational databases, particularly DB2, but am trying to prototype something in Access just to see how it compares. I'm in design mode in Access 2013 and am trying to create a simple table with just two columns, Meeting_Date, which will contain a date in the format YYYY-MM-DD ("short date" in Access terms), and Meeting_Comment, which is defined as a Long Text field. I've defined a Primary Key on Meeting_Date and I've deleted the autonumbered ID field that Access generates automatically as the first column in a table. All of that went fine.
However, when I try to rename the table, it tells me that I need to Save the table first. I suppose that's reasonable. When I try to save the table, it complains that "Index or Primary Key cannot contain a null value". I understand that Primary Keys cannot contain null values. In fact, I expect that defining a column as a Primary Key will ensure that Access will not accept a null Primary Key value: that's certainly what happens in DB2. I am completely baffled why I am getting this message NOW since the table contains NO DATA yet.
What do I need to do to be able to save this very simple table? Also, can I be sure that when I have successfully saved the table, that any row for which I supply a null Primary Key will be rejected by Access? (By the way, if I'm inserting a row with a form or the table view, how do I indicate a null, as opposed to a blank? Or will Access treat an empty input field as a null automatically?)