我怎样才能访问bookshelf.js中的knex / querybuilder raw？

Question

这不起作用

let rawResult = await AuthorModel.query((qb) => {

  qb.column(Bookshelf.knex.raw('SELECT LEFT(authors.last_name, 1) AS first_char'));

});

这也不起作用：

let rawResult = await AuthorModel.query((qb) => {

  qb.column(AuthorModel.knex.raw('SELECT LEFT(authors.last_name, 1) AS first_char'));

});

这也不起作用：

let rawResult = await AuthorModel.query((qb) => {

  qb.column(qb.raw('SELECT LEFT(authors.last_name, 1) AS first_char'));

});

我的想法和选择都用光了。