confusion about how connection.end() works in node.js mySQL module

Question

const mysql = require('mysql'); 
let connection = mysql.createConnection(...);
        connection.connect((err)=>{
           ...
           connection.query((err)=>{
           ...
           connection.end();});
        });

After I close the connection by using

connection.end()

, if I want to query the database again using the same credentials, do I need to make a new connection by calling

mysql.createConnection(...)

Or can I reuse the same connection by simply calling

connection.connect(...)

A little background: I'm deploying an angular/node.js app to a shared hosting website, and the web host has a maximum limit of 25 concurrent connections to mySQL database, therefore I need to make sure I close a connection properly after a user does his query. I am not sure if I could reuse the connection created by mysql.createConnection(...) after I close that connection, or do I need to create a brand new connection.

Answer 1

You can use one global connection for getting data from db .

If You working on single file than you can write as

app.js one file only

 var mysql      = require('mysql');
 var connection = mysql.createConnection(...);

    connection.query('SELECT 1', function (error, results, fields) {
     if (error) throw error;
   // connected!
  });

if you want to use same connection in multiple file than you can write as
app.js

 app.use(  
    connection(mysql, {
         host: xxxxx, 
         user: 'root',
         password : xxxx, 
         port : 3306, 
         database:dbname

     },'pool'),  
   );

  var oem = require('./routes/type');
  app.get('/api/oemtype',oem.type);

For the second file type.js

   exports.type = function(req, res){

     req.getConnection(function(err,connection){

      var query = connection.query('SELECT * FROM type',function(err,rows)
      {
          if(err)
          res.json({
            status:0
        });

              res.send(rows);
         res.render('customers',{page_title:"Customers - Node.js",data:rows});


       });

  });

   };

No need to use of connection.end().