app.py

from flask import Flask, render_template
from flask_sqlalchemy import SQLAlchemy
from flask import Flask, render_template, request,redirect,flash


app = Flask(__name__)
app.config["SQLALCHEMY_DATABASE_URI"] = "sqlite:///employee.db"		# initialising sqlacheemy connectiong it woth my database and creting a database name employee
app.config["SQLALCHEMY_TRACK_MODIFICATIONS"] = False
app.config['SECRET_KEY'] = 'supersecretkey'

db = SQLAlchemy(app)
app.app_context().push() #written to create a database

class Employee(db.Model):						#model here works beacuse flask works on MVC - model view controller
    sno = db.Column(db.Integer, primary_key = True)			
    name = db.Column(db.String(200), nullable = False)			
    email = db.Column(db.String(500), nullable = False)

@app.route("/",methods=['GET','POST'])
def home():
    if request.method == 'POST':
        name=request.form.get('name','').strip()
        email=request.form.get('email','').strip()

        if not name or not email:
            flash("all fields ar required", "danger")
            return redirect("/") 
        employee = Employee(name = name, email = email)	
        db.session.add(employee)							
        db.session.commit()		
        
        flash("form submitted successfully", "Success")
        return redirect("/")

    allemployee=Employee.query.all()
    return render_template("index.html",allemployee=allemployee)

@app.route("/delete/<int:sno>")
def delete(sno):
    employee = Employee.query.filter_by(sno=sno).first()
    db.session.delete(employee)
    db.session.commit()
    return redirect("/")


@app.route("/about")
def about():
    return render_template('about.html')
    #return "<p>This is my about page</p>"

@app.route("/update/<int:sno>", methods=['GET', 'POST'])
def update(sno):
    employee = Employee.query.filter_by(sno=sno).first()

    if request.method == 'POST':
        name = request.form.get('name', '').strip()
        email = request.form.get('email', '').strip()

        if not name or not email:
            flash("All fields are required", "danger")
            return redirect(f"/update/{sno}")

        employee.name = name
        employee.email = email
        db.session.commit()   # no need for db.session.add()

        flash("Employee updated successfully", "success")
        return redirect("/")

    return render_template("update.html", employee=employee)

if __name__ =='__main__':
    app.run(debug=True)