Flask SQLAlchemy



  • Flask SQLAlchemy is an ORM tool.
  • It is establishes the relationship between the objects and the tables of the relational databases.
  • The object-relational mapping is the technique of storing python objects into the database tables without writing the raw SQL queries.

Install flask-sqlalchemy:

  • Using pip installer, we must need to install flask-sqlalchemy. $ pip install flask-sqlalchemy
  • To confirm the installation, We need to import the module on the python shell. If it is successfully imported, the installation is successful. $ import flask_sqlalchemy

Creating a small web application using flask-sqlalchemy

Here we will create a CRUD Application in python using ORM SQLAlchemy.

Sample Code


<!DOCTYPE html>  
      <h3>Add new Employee</h3>  
      {%- for category, message in get_flashed_messages(with_categories = true) %}  
         <div class = "alert alert-danger">  
            {{ message }}  
      {%- endfor %}  
      <form action = "{{ request.path }}" method = "post">  
         <label for = "name">Name</label><br>  
         <input type = "text" name = "name" placeholder = "Name" /><br>  
         <label for = "salary">Salary</label><br>  
         <input type = "text" name = "salary" placeholder = "salary" /><br>  
         <label for = "age">Age</label><br>  
         <textarea name = "age" placeholder = "age"></textarea><br>  
         <label for = "PIN">Pin</label><br>  
         <input type = "text" name = "pin" placeholder = "pin" /><br>  
         <input type = "submit" value = "Submit" />  


<!DOCTYPE html>  
<html lang = "en">  
         <a href = "{{ url_for('list_employees') }}">Employee Management System</a>  
      {%- for message in get_flashed_messages() %}  
         {{ message }}  
      {%- endfor %}  
      <h3>Employees List</h3>  
      <table border="2" padding = "5">  
<thead>              <tr>  
            {% for employee in Employees %}  
                  <td>{{ employee.name }}</td>  
                  <td>{{ employee.salary }}</td>  
                  <td>{{ employee.age }}</td>  
                  <td>{{ employee.pin }}</td>  
            {% endfor %}  
      <a href="{{ url_for('addEmployee') }}">Add New Employee</a>  


from flask import Flask, request, flash, url_for, redirect, render_template  
from flask_sqlalchemy import SQLAlchemy  
app = Flask(__name__)  
app.config['SQLALCHEMY_DATABASE_URI'] = 'sqlite:///employees.sqlite3'  
app.config['SECRET_KEY'] = "secret key"  
db = SQLAlchemy(app)  
class Employees(db.Model):  
   id = db.Column('employee_id', db.Integer, primary_key = True)  
   name = db.Column(db.String(100))  
   salary = db.Column(db.Float(50))  
   age = db.Column(db.String(200))   
   pin = db.Column(db.String(10))  
   def __init__(self, name, salary, age,pin):  
      self.name = name  
      self.salary = salary  
      self.age = age  
      self.pin = pin  
def list_employees():  
   return render_template('list_employees.html', Employees = Employees.query.all() )  
@app.route('/add', methods = ['GET', 'POST'])  
def addEmployee():  
   if request.method == 'POST':  
      if not request.form['name'] or not request.form['salary'] or not request.form['age']:  
         flash('Please enter all the fields', 'error')  
         employee = Employees(request.form['name'], request.form['salary'],  
            request.form['age'], request.form['pin'])  
         flash('Record was successfully added')  
         return redirect(url_for('list_employees'))  
   return render_template('add.html')  
if __name__ == '__main__':  
   app.run(debug = True)  
 Employe Management System

Employe Management System

  • Click on the link Add new Employee
 Add New Employee

Add New Employee

  • Click on Submit, and we will see the newly added employee in the list on the home page.

Added Employee

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