How do I use a specific columns value in Node JS using SQL

Question

I was wondering how to I select a specific column to save to a variable in my function. I need both values which is why I have a query getting both at once. I'm using Node JS with an Azure SQL Database and I'm using tedious for my SQL NPM plugin. I'm fairly new to this so any help would be appreciated. Thanks!

Side note: the request "on done" at the very bottom that returns the row count isn't doing anything. If anyone knows why I'd love to know, it's not important but I'm just curious.

function Charge(chipId, LocID) {
        request = new Request("SELECT car_id, userOwner FROM Cars WHERE carChipId = '" + chipId + "'", function (err) {
            if (err) {
                console.log(err);
            }
        });
        var result = "";
        request.on('row', function (columns) {
            columns.forEach(function (column) {
                if (column.value === null) {
                    console.log('NULL');
                } else {
                    result += column.value + " ";
                }
            });
            console.log(result);
            result = "";
        });

        request.on('done', function (rowCount, more) {
            console.log(rowCount + ' rows returned');
        });
        connection.execSql(request);
    }

Aaron Chen · Accepted Answer · 2016-12-30 07:35:05Z

2

Trying the following to select a specific column saved to the variable:

function charge(chipId) {
  var carId = '';
  var userOwner = '';

  request = new Request(`SELECT car_id, userOwner FROM Cars WHERE carChipId = '${chipId}'`, function(err) {
    if (err) {
      console.log(err);
    }
  });

  request.on('row', function(columns) {

    carId = columns[0].value;
    userOwner = columns[1].value;
    console.log('carId: ', carId);
    console.log('userOwner: ', userOwner);
  });

  connection.execSql(request);
}

Another option is that you can set options.useColumnNames as true (Default: false) to return rows as key-value collections. Below is the code example.

var config = {
  userName: '<userName>',
  password: '<password>',
  server: '<serverName>.database.windows.net',

  options: {
    encrypt: true,
    database: '<database>',
    useColumnNames: true
  }
};

var connection = new Connection(config);

connection.on('connect', function(err) {
  charge('<chipId>');
});

function charge(chipId) {
  var carId = '';
  var userOwner = '';

  request = new Request(`SELECT car_id, userOwner FROM Cars WHERE carChipId = '${chipId}'`, function(err) {
    if (err) {
       console.log(err);
    }
  });

  request.on('row', function(columns) {
    carId = columns.car_id.value;
    userOwner = columns.userOwner.value;
    console.log('carId: ', carId, ' userOwner: ', userOwner);
  });

  connection.execSql(request);
}

If you wanna Event: done be triggered, please use connection.execSqlBatch(request) instead of connection.execSql(request). For details, please refer to http://tediousjs.github.io/tedious/api-connection.html#function_execSqlBatch.

answered Dec 30, 2016 at 7:35

Aaron Chen

9,9701 gold badge20 silver badges30 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Luc Over a year ago

I also can't seem to do more than one request from a single connection.on('connect', for whatever reason, is there something else I should know?

Aaron Chen Over a year ago

There is some documentation at tediousjs.github.io/tedious/api-connection.html that states that this is not supported. Only one request at a time may be executed on a connection. You can use mutiple connections instead. This post may be helpful.

Luc Over a year ago

Ok, I made another post about this topic would you mind reviewing my situation to make sure it would work?

Aaron Chen Over a year ago

I looked into this and I will share details after lunch.

Collectives™ on Stack Overflow

How do I use a specific columns value in Node JS using SQL

1 Answer 1

4 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

4 Comments

Your Answer

Sign up or log in

Post as a guest

Related