Connection

var mysql = require('mysql2');
var db = mysql.createConnection({
host: "localhost",
user: "root",
password: "",
database: "students_db"
});

Fetch (Server)

app.get('/fetch', (req, res) => {
const q = "SELECT * from students"
db.query(q,(err,data)=>{
if(err) return res.json(err)
return res.json(data) 
})
})

Fetch (Client)

const [data, setData] = useState([])
useEffect(() => {
    axios.get('http://localhost:3000/fetch')
        .then(res => setData(res.data))
        .catch(err => console.log(err))
}, [])

Create (Server)

app.post('/create',(req,res)=>{
const {id, name, roll, fees, classs,medium} = req.body
const q = 'INSERT INTO students(id, name, roll, fees, class, medium) VALUES (?,?,?,?,?,?)'
db.query(q, [id, name, roll, fees, classs, medium],(err,data)=>{
if(err) return res.json(err)
return res.json(data) 
})
})

Create (Client)

const handleSubmit = (e) => {
    e.preventDefault()
    const id = e.target.id.value;
    const name = e.target.name.value;
   
    const values = { id, name}
    axios.post('http://localhost:3000/create', values)
        .then(res => console.log(res.data))
        .catch(err => console.log(err))
}

Delete (Server)

app.delete('/cartItems', (req, res) => {
const { email, id } = req.query; 
const sqlQuery = "DELETE FROM cart WHERE email = ? AND _id = ?";
db.query(sqlQuery, [email, id], (err, result) => {
  if (err) {
    console.log(err)
      return res.status(500).send('Error deleting cart item');
  }
  res.status(200).send('Cart item deleted successfully');
});
});

Delete (Client)

function handleDelete(x){

const id = x._id;       
axios.delete(`http://localhost:3000/cartItems?email=${user?.email}&&id=${id}`) 
then(res => console.log(res.data))
.catch(err => console.log(err));         
    
}

Add Unique Email To DB

app.post('/userInfo',(req,res)=>{
const {name,email} = req.body
const q ="INSERT INTO user_info (name, email) SELECT ?, ? WHERE NOT EXISTS (SELECT 1 FROM user_info WHERE email = ?)";
db.query(q, [name,email,email],(err,data)=>{
if(err) return res.json(err)
return res.json(data) 
})
})