SQL Case Statement - how to do it

I have the below statement which works nicely in Tableau.

However, I'd like to turn this into SQL and save all the results into a temporary column name.

Does anyone know how I might do this?

Essentially, the below removes the .com/.net etc... from the domain name.

I then have another script that removes the subdomain (everything from the first . to the left of the resulting value).

If anyone can help me with these, that would be incredible as I'm not sure how to do this in SQL

IF CONTAINS([domain], ".co.uk") then LEFT([domain],LEN([domain])-6)
elseif  CONTAINS([domain], ".com") then LEFT([domain],LEN([domain])-4)
elseif  CONTAINS([domain], ".net") then LEFT([domain],LEN([domain])-4)
elseif  CONTAINS([domain], ".org") then LEFT([domain],LEN([domain])-4)
elseif  CONTAINS([domain], ".biz") then LEFT([domain],LEN([domain])-4)
elseif  CONTAINS([domain], ".edu") then LEFT([domain],LEN([domain])-4)
elseif  CONTAINS([domain], ".ac") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".gov") then LEFT([domain],LEN([domain])-4)
elseif  CONTAINS([domain], ".biz") then LEFT([domain],LEN([domain])-4)
elseif  CONTAINS([domain], ".co") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".ca") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".io") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".in") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".it") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".uk") then LEFT([domain],LEN([domain])- 3)
elseif  CONTAINS([domain], ".ru") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".ie") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".tv") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".info") then LEFT([domain],LEN([domain])-5)
elseif  CONTAINS([domain], ".fr") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".es") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".pl") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".is") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".hu") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".xxx") then LEFT([domain],LEN([domain])-4)
elseif  CONTAINS([domain], ".nl") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".ro") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".xyz") then LEFT([domain],LEN([domain])-4)
elseif  CONTAINS([domain], ".no") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".eu") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".me") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".cz") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".fi") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".nl") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".al") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".am") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".af") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".st") then LEFT([domain],LEN([domain])-3)
elseif  CONTAINS([domain], ".cn") then LEFT([domain],LEN([domain])-3)
else [domain]
end