我想要在mongoose中转换以下mysql查询

const mongoose = require('mongoose');

mongoose.connect('mongodb://localhost:27017/mydatabase', {
  useNewUrlParser: true,
  useUnifiedTopology: true,
});

const mongoose = require('mongoose');

const userSchema = new mongoose.Schema({
  name: String,
  age: Number,
  email: String,
});

const User = mongoose.model('User', userSchema);

User.find({}, (err, users) => {
  if (err) {
    console.error(err);
  } else {
    console.log(users);
  }
});

User.find({ age: { $gt: 18 } }, (err, users) => {
  if (err) {
    console.error(err);
  } else {
    console.log(users);
  }
});

User.findOne({ name: 'John' }, (err, user) => {
  if (err) {
    console.error(err);
  } else {
    console.log(user);
  }
});

const newUser = new User({
  name: 'John',
  age: 25,
  email: 'john@example.com',
});

newUser.save((err, savedUser) => {
  if (err) {
    console.error(err);
  } else {
    console.log(savedUser);
  }
});

User.updateOne({ name: 'John' }, { age: 26 }, (err, result) => {
  if (err) {
    console.error(err);
  } else {
    console.log(result);
  }
});

User.deleteOne({ name: 'John' }, (err) => {
  if (err) {
    console.error(err);
  } else {
    console.log('User deleted');
  }
});