If you need to convert strings to all upper case or all lower case, you can use the UPPER and LOWER functions in T-SQL as shown below:
These are simple functions and it doesn't matter what those strings were to start with, it will just do the case conversion.
It's also worth noting that if you want to make your SQL query text change to upper or lower case in SQL Server Management Studio, there's a shortcut for that too. If you want to just quickly convert a string to all uppercase or all lower case, just highlight the string and hit control shift U for upper or control shift L for lower.
What we are missing in T-SQL though is other casing options like PascalCase, Title Case, Proper Case, camelCase, snake_case, etc. If you need those, I'd suggest you look at the string functions in our free SDU Tools for developers and DBAs. We have a large number of casing options, even including a Sponge Bob casing option !
It's worth your while becoming proficient in SQL. If you'd like to learn a lot about T-SQL in a hurry, our Writing T-SQL Queries for SQL Server course is online, on-demand, and low cost.