How to connect my react native expo project with MySQL? [duplicate] - mysql

Question

I'm using React Native. I want to find the data I entered in React Native in the database. For example, in the database of the user name I entered, "select id from table where ('data I entered in react native')". I want to find the table with the user name and pull the user's id.
var name = this.state.username;
"select id from table where (name)"
I want to pull the id of the user name like this.

Answer 1

There is no direct connection between RN and Mysql. Use Node js for this.
Step: 1
npm install express
npm install body-parser
npm install mysql
Step: 2
const connection = mysql.createPool({
host : 'localhost', // Your connection adress (localhost).
user : 'root', // Your database's username.
password : '', // Your database's password.
database : 'my_db' // Your database's name.
});
// Starting our app.
const app = express();
// Creating a GET route that returns data from the 'users' table.
app.get('/users', function (req, res) {
// Connecting to the database.
connection.getConnection(function (err, connection) {
// Executing the MySQL query (select all data from the 'users' table).
connection.query('SELECT * FROM users', function (error, results, fields) {
// If some error occurs, we throw an error.
if (error) throw error;
// Getting the 'response' from the database and sending it to our route. This is were the data is.
res.send(results)
});
});
});
// Starting our server.
app.listen(3000, () => {
console.log('Go to http://localhost:3000/users so you can see the data.');
});
Now, how do we get that data on our React Native App?
That's simple, we use the fetch function.
To do that, instead of using 'localhost:3000', you'll have to directly insert your PC's ip adress. If you use 'localhost', you're acessing your smartphone/emulator's localhost. And that's not what we want. Follow this example:
test(){
fetch('http://yourPCip:3000/users')
.then(response => response.json())
.then(users => console.warn(users))
}

Answer 2

You need to have a backend service/API in order to fetch data from database. try using Node, and write a simple backend since its JavaScript. You can execute sql queries on backend, retrive data from mySQL to your node server and then you can fetch data from the backend server to react-native using fetch method. (both your backend API and the device that running react native application should be running on the same network.)