UpperCase Replace(Split_Part()) - sql

Question

Community,
I need assistance with removing the UNDER SCORES '_' and make the name readable first name letter UpperCase last name UpperCase, while removing the number as well. Hope this makes sense. I am running Presto and using Query Fabric. I there a better way to write this syntax?
Email Address
Full_Metal_Jacket#movie.com
TOP_GUN2#movie.email.com
Needed Outcome
Full Metal Jacket
Top Gun
Partical working Resolution:
,REPLACE(SPLIT_PART(T.EMAIL, '#', 1),'_',' ') Name
Something like this:
,LOWER(REPLACE(UPPER(SPLIT_PART(T.EMAIL, '#', 1)),'_',' '))Name

Answer 1

Try this:
WITH t(email) AS (
VALUES 'Full_Metal_Jacket#movie.com', 'TOP_GUN2#movie.email.com'
)
SELECT array_join(
transform(
split(regexp_extract(email, '(^[^0-9#]+)', 1), '_'),
part -> upper(substr(part, 1, 1)) || lower(substr(part, 2))),
' ')
FROM t;
How it works:
extract the non-numeric prefix up to the # using a regex via regexp_extract
split the prefix on _ to produce an array
transform the array by capitalizing the first letter of each element and lowercasing the rest.
Finally, join them all together with a space using the array_join function.
Update:
Here's another variant without involving transform and the intermediate array:
regexp_replace(
replace(regexp_extract(email, '(^[^0-9#]+)', 1), '_', ' '),
'(\w)(\w*)',
x -> upper(x[1]) || lower(x[2]))
Like the approach above, it first extracts the non-numeric prefix, then it replaces underscores with spaces with the replace function, and finally, it uses regexp_replace to process each word. The (\w)(\w*) regular expression captures the first letter of the word and the rest of the word into two separate capture groups. The x -> upper(x[1]) || lower(x[2]) lambda expression then capitalizes the first letter (first capture group -- x[1]) and lower cases the rest (second capture group -- x[2]).