ModuleNotFoundError: No module named 'first' - python-3.x

Question

I am trying to make a database in my terminal but when I try it I always get this error when I use from first import db:
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ModuleNotFoundError: No module named 'first'
Here is my code
from flask import Flask, render_template
from flask_sqlalchemy import SQLAlchemy
from datetime import datetime
app = Flask(__name__)
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///posts.db'
db = SQLAlchemy(app)
class BlogPost(db.Model):
id = db.Column(db.Integer, primary_key= True)
Title = db.Column(db.String(100), nullable= False)
Content = db.Column(db.Text, nullable= False)
Date_posted = db.Column(db.DateTime, nullable= False, default=datetime.utcnow)
def __repr__(self):
return "Blog Post" + str(self.id)
all_posts = [
{
'Title': 'Post 1',
'Content': "This is the first content"
},
{
'Title': 'Post 2',
'Content': 'This is the second content'
}
]
#app.route('/')
def index():
return render_template("index.html")
#app.route('/blog-posts')
def blog_posts():
return render_template("posts.html", posts = all_posts)
#app.route('/home')
def hello():
return "My first python website"
if __name__ == '__main__':
app.run(debug= True)
I only have python 3.8 installed.
What could be the problem? I've searched the internet and used every advice on other platforms yet no solution. Flask and flask-sqlalchemy are installed properly.
This is the youtube video I use as a guide when creating this project:
https://www.youtube.com/watch?v=3mwFC4SHY-Y

Answer 1

Well I am assuming you have created a python file named first. I am listing out what could have been gone wrong:
You are in the wrong directory.
You have not installed the necessary package. (unlikely)
According to the tutorial, the file name is app.py so there he performs from app import db. Just make sure you have the name of the file correct.
I am not able to think of any other probable cause, unless first is a package create by you to store the project's python files like routes.py, models.py, etc. In that case you need to have __init__.py file in the package directory and initialize app and db in __init__.py file