If you want to evaluate more complex expression, the only easy way I know is with the SQL.NET product. It evaluates .NET expression directly in SQL stored procedure, function and trigger.

-- CREATE expression

DECLARE @sqlnet SQLNET = SQLNET::New('8*(1/2)-6')

-- EVALUATE expression

SELECT @sqlnet.Eval() -- (return: -6)quote]

Here is the product link:

https://github.com/zzzprojects/Eval-SQL.NET

You can also use the .NET Runtime Compiler if you want to evaluate in your own CLR procedure:

https://github.com/zzzprojects/Eval-Expression.NET

Let me know if it worked for you.