Learned this from a friend. The types are null, integer, real, text, and blob. My friend describes them thusly:
- Null stores nothing, but like, actively nothing, as opposed to the absence of a thing.
- Integer is a signed integer, up to 8 bytes.
- Real is always an 8-byte float.
- Text is an arbitrary-length UTF-8 or UTF-16.
- Blob is an arbitrary-length anything-else. But I hope you remembered what you put there. Because it sure isn’t gonna tell you. Oh, and it doesn’t have strong typing, so if you ask for it back as an integer, it’ll quite happily give you it back as an integer, especially if that doesn’t make sense!
Conceptually, as in what the null represents at the DB level, yes. Logically, at the software level, I’d say sort of, but not really. It’s complicated. Does it make sense to compare values of fundamentally different types?
In a system like Java’s where everything derives from a common
objectclass one can saynullis a valid value ofobjecttype, so any two null values are equivalent. With ANSI nulls, even null isn’t equivalent to null.