如何在Knex中编写MySQL子查询？

const knex = require('knex')({
  client: 'mysql',
  connection: {
    host: 'your_host',
    user: 'your_user',
    password: 'your_password',
    database: 'your_database'
  }
});

knex
  .select('name', 'age')
  .from(function() {
    this.select('name', 'age')
      .from('users')
      .where('age', '>', 18)
      .as('subquery');
  })
  .then(rows => {
    console.log(rows);
  })
  .catch(err => {
    console.error(err);
  })
  .finally(() => {
    knex.destroy();
  });