Question about licensing / legality

I'm new to Rust and really not far past the Hello World stage and using some crates. I have developed in other languages for years though so I'm not a complete noob.

Anyways - what is the legality / licensing of using crates? So suppose I write my Rust code and I use a crate to interact with SQL Server...

Does my code have to be published under an open source license?

What if I want to charge for my code? I'm using someone else's SQL Server crate so how does that work?

What if its the other way around - I want to open source my code under GPL but someone's crate is under MIT?

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So I'm just checking all of this out because it seems more 'invisible' to use crates than in other languages. I'm not complaining by any means I just want to understand the DOs and DON'Ts of using other people's code and investment of time.