sql - Difference between a inline function and a view

Question

I am a newbie in using functions and it appears to me that an inline function is very similar to a view. Am I correct?

Also, can I have UPDATE statements within a function?

Answer 1

After reading many of the answers here, I'd like to note that there is a big difference between an inline table-valued function and any other kind of function (scalar or multi-line TVF).

An inline TVF is simply a parameterized view. It can be expanded and optimized away just like a view. It is not required to materialize anything before "returning results" or anything like that (although, unfortunately, the syntax has a RETURN.

A big benefit I've found of an inline TVF over a view is that it does force required parameterization whereas with a view, you have to assume that the caller will appropriately join or restrict the usage of the view.

For example, we have many large fact tables in DW with a typical Kimball star model. I have a view on a fact table-centered model, which called without any restriction, will return hundreds of millions of rows. By using an inline TVF with appropriate parameterization, users are unable to accidentally ask for all the rows. Performance is largely indistinguishable between the two.