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Comment by elchief | Hacker News Reader

You're gonna need nulls until databases stop supporting nulls. And everyone would need to use 6th normal form for that to happen, and nobody wants that

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Not true. Nullable values in a database can be dealt with (and I would argue _should_ be dealt with) using a maybe/option[1] type. This is exactly what Slick[2] does, for example.

[1] https://en.wikipedia.org/wiki/Option_type [2] http://slick.lightbend.com/

Could you explain why you believe the presence of a NULL in the database necessitates a NULL pointer somewhere in the code?

I believe the author's intent is if you read a null value out of a database, how would you represent it in code?

I think it depends on where the NULL is and what it represents.

If NULL value is in a field that is used for JOIN-ing, I don't think you would "represent" the NULL value as much as you would simply have a lack of data. For example, if you had some set of results from a query that contained a JOIN on a field and some values were NULL, those records with the NULL value would not be in the result set.

If we do receive results with possibly NULL values I believe they could be either be represented with an appropriate zero value -- e.g. "" or 0 -- or with an optional type like another commenter suggested.

.NET uses DBNull.Value, which is not null.

Also 6th normal form?? What is that?

You store each letter in the names of the columns of your tables in a different data center.

https://en.wikipedia.org/wiki/Sixth_normal_form

Not something I'd like to use.

I work with an engineering application that uses a 5th/6th normal form database that is implemented in standard SQL server/Oracle DBs. It is awful and painful. A simple query with maybe five properties and 2 relationships takes upwards of 20 joins. Yet the database only has 4 tables...

Null references to memory are what is being discussed, which is completely different from variant/option types. Changing databases has nothing to do with NULL references to memory.

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