Dynamically Max Value Found to Any Table With Criteria

DECLARE
@FIELDNAME VARCHAR(50)='',
@TABLENAME VARCHAR(50)='',
@WHERECLAUSE VARCHAR(MAX)=''
AS
BEGIN


    DECLARE @RESULT VARCHAR(MAX)=''
IF @WHERECLAUSE <> ''
BEGIN    
SET @RESULT ='SELECT MAX(' + @FIELDNAME + ') FROM ' + @TABLENAME + ' WITH(NOLOCK)  WHERE '+ @WHERECLAUSE
END
ELSE
    BEGIN
        SET @RESULT ='SELECT MAX(' + @FIELDNAME + ') FROM ' + @TABLENAME + ' WITH(NOLOCK)'
    END
EXEC (@RESULT)
END