Delete Query in flask, python and SQLAlchemy

Delete Query in flask, python and SQLAlchemy

 

To perform a delete query in Flask using SQLAlchemy, you can follow these steps:

1. Import the necessary modules:

from flask import Flask

from flask_sqlalchemy import SQLAlchemy

2. Create an instance of Flask and SQLAlchemy:

app = Flask(__name__) app.config['SQLALCHEMY_DATABASE_URI'] = 'your_database_uri_here' db = SQLAlchemy(app)

3. Define the model for the table you want to delete from. For example, if you have a table named users with columns id, name, and email, you can define the model as follows:

class User(db.Model): id = db.Column(db.Integer, primary_key=True) name = db.Column(db.String(50), nullable=False) email = db.Column(db.String(120), unique=True, nullable=False)

4. To delete a row from the users table with a specific id, you can use the following code:

user = User.query.get(id) db.session.delete(user) db.session.commit()

Where id is the primary key value of the row you want to delete. This code retrieves the row with the specified id using the query.get() method, deletes it using db.session.delete(), and then commits the transaction using db.session.commit().

5. If you want to delete multiple rows based on some condition, you can use the filter() method. For example, to delete all users whose name is "John", you can use the following code:

User.query.filter_by(name='John').delete() db.session.commit()

This code uses the filter_by() method to filter the rows based on the name column, and then calls the delete() method to delete all the matching rows. Finally, it commits the transaction using db.session.commit().

Happy Learning!! Happy Coding!!