Databases Reporting with SQL Working with Text Getting the Length of a String

Finding data and using alias

In the library database there's a books table with the columns id, title, author, genre and first_published. Find the book with the longest title. Show the title and then the length. Alias the result of the length calculation to be longest_length. Only retrieve the longest book.

My answer: SELECT title FROM books WHERE "length" AS "longest_length" DESC LIMIT 1;

I am getting the answer incorrect can anyone explain what I am doing wrong please