Japanese- dake and shika?

Question:

From what I've learned, dake means only, and shika means except when you put the verb or adjective in a negative tense. But some translate both dake and shika to only, so it gets me pretty confused.

So if I wanted to say He's just weird, it would be: kare wa ha na/ okashii dake desu. (ha na and okashii both mean weird or strange ,right?)
And if I wanted to say Only he's weird, it would be: kare dake ha/ okashii desu. Please correct me if I'm wrong.


Now I feel like I have no idea how to use shika. I've come across some confusing sentences, such as: Jonh shika konakatta. Which translates to only john came. Learning shika means except, I thought it would be everyone except john came. Another one that really puzzled me was: kimi shika aitakunai no. Translated to, I only want to meet you. Again, I thought this would mean I want to meet everyone except you, or something like that.

One last thing, what does dake shika nai mean :)?

So if anyone could help me make sense of this, and give me some easy romaji examples, that would be terrific. I'm really struggling with the matter, so any help is appreciated. Thank you in advance for your answers, if choosing to answer.

Answer:

Both mean the same: Only.
Dake is used in both affirmative and negative forms.
Shika is used in negative form only.
Ex.
Dake
1. Tom wa green tea Dake nomu (affirmative): Tom drinks green tea only.
2. Tom wa green tea Dake nomanai (negative): Tom does not drink green tea (but drinks everything else) or Tom drinks everything but green tea.

Shika
1.Tom wa green tea Shika nomanai (negative): Tom drinks green tea only.
Dakeshika is a stressing form of Shika, used in negative form only.