interrogative sentences with WH-clauses in the middle

Question

I know that when we are reporting a question in a sentence in reported speech, the question mark should be removed, like this:

Question asked of me: "Did you know that girl?"
Reported: He asked me if I had known the girl.

But what about the case where the question has a with a wh-clause?

As in:

"Do you know where...?"

"Do you know where I can get a handmade knife?"

If the above question sounds correct, why doesn't the one below?

Do you know where can I get a handmade knife?

I'd like the name for the grammar involved here, and an explanation of why the word order is switched.

Answer 1

The rule is simple: if the main clause is question then the sentence counts as a question and you put a question mark, So

Do you.. ?

He asked.. .

But I'm not sure what you are looking for a grammatical term to describe. (Note no question mark in that sentence!)

Answer 2

In regards to your last question... You are essentially asking:

Do you know X?

In this case, X is the bit of information about where I can get a handmade knife. That part is not a question but rather a description of a piece of information you're seeking.

If you drop the Do you know part, then, yes, your question would need to be:

Where can I get a handmade knife?

In the first example, the part beginning with where is not a question; in the second one, it is.