functions in sqlserver ?

Question

Hi

 

 These days while facing interviews facing some typical scenarios  to get required output ..

 

What i need is just in order to implement what i think actually there are functions already available in sqlserver like  STUFF,OVER,COLESELE like this many

 

I request can anyone give me You tube videos link on this functions like above can help it .

If no videos links atleast givvme a best resource to know such stuff in simple manner 

 

My best Regards