How to make a query with Node.js and Mysql

Question

Hello, I’m starting with Node.js and MySQL, and I have some problems at the moment. Well, I have a table called users, and I need to request data for verification, for example: My site has a registration form, but you need to check the data to see if there is a user already registered with the same data.

My code is like this so far:

 var pool  = mysql.createPool({
  host     : 'localhost',
  user     : 'root',
  password : '',
  database:'tabela'
});

pool.getConnection(function(err, connection) {
  // Use the connection
  var email = emailCadastro;
  connection.query( 'SELECT * FROM usuarios WHERE email = ?',[email], function(err, rows) {
    // And done with the connection.
    connection.release();

    // Don't use the connection here, it has been returned to the pool.
    console.log(rows[0].email);
  });
});

Please correct me if this code is wrong. The variable emailCadastro comes from the user’s form.

The interpreter returns the following error:

Cannot read property 'email' of undefined

I wonder what the mistake is here and if anyone could help me.

Answer 1

Following the Node-mysql documentation this method only accepts 2 arguments. The query and the callback.

If what you need is to pass the email to the query then you should concatenate it with + which is the concatenation symbol in Javascript. I suggest you change the code as I put it below (eventually you may have to take the quotes around that string with the mail):

pool.getConnection(function(err, connection) {
  // Use the connection
  var email = emailCadastro;
  connection.query( 'SELECT * FROM usuarios WHERE email="' + email + '"', function(err, rows) {