Roy Lambert wrote:

>  I like the idea of null meaning "we haven't put anything in here yet"

Indeed - that's what it can be used to mean. The integers are a better example too - if you have three transactions on an account, one is a purchase, one is a refund, and the other is a change of address. Each can have a money paid value. 100, -15, and NULL. Now you can be clear about what you have in the way of financial transactions, without having to be clever about having another column to control whether you include the value or not. I'd hope (and am pretty sure it does) that SQL would average only two rows there, for example.

NULL isn't a magic anything, but it makes sense to have it as an option. And indeed, defining a column with a default of an empty string is fine really - why not?  You are sort of ignoring the NULLable aspect, while keeping it as an option for other columns. Turning off NULLs means you lose that option.

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Matthew Jones

Matthew


Please note that at no time (to the best of my recollection) have I said I don't like the concept of NULL. I'm just arguing against using it for the wrong things (in my view) and pretending an emptystring exists.

Roy Lambert