I take a tutorial to save date on Firebase in React Native.
When i compile it that show the error is _firebase2.default.database.ref is not a function
But the question that offcial tutorial is  .ref too.
https://firebase.google.com/docs/database/web/read-and-write
Any one can teach me how to solve the issue , thanks in advance.
My rules setting on Firebase:
{
  "rules": {
    "users": {
      "$uid": {
        ".read": "$uid === auth.uid",
          ".write": "$uid === auth.uid"
      }
    }
  }
}
Save data code in React Native:
export const employeeCreate = ({ name, phone, shift }) => {
    const { currentUser } = firebase.auth();
    firebase.database.ref(`/users/${currentUser.uid}/employees`)
    .push({ name, phone, shift });
};