use variable as column name in where clause in sql

I want to use a variable as column name in my SQL query.

Problem:

I can not use dynamic SQL as the SQL query that I have is inside of a user defined inline table function.

What are other possible alternatives?

My code is as follows:

create function MatchStringPercent(@parameterFromUser nvarchar(20), @parameterInTable nvarchar(20))
RETURNS table As Return 
SELECT Top(1)
cast(LEN(@parameterInTable) as float)/(Abs(LEN(@parameterFromUser) - LEN(@parameterInTable)) + LEN(@parameterInTable))* 100 As Match
FROM Demo
WHERE @parameterInTable = LEFT( @parameterFromUser , LEN(@parameterInTable) ) 
ORDER BY LEN(@parameterInTable) DESC 
Go