I am querying a mySQL database from the context of Node.js server code. Generally speaking, things are working fine. However, I can't figure out a way to tell whether an UPDATE statement does not update any rows. For instance, if I have code such as:

connection.query("UPDATE table SET columnA = valA WHERE columnB = valB;",
    function(err, rows, fields) {

   ..some code..
}

As far as I can tell, none of the callbacks (err, rows, fields) will provide me with any information informing me that zero rows were affected. This is important information to me. How can I resolve this? Thanks!

I am querying a mySQL database from the context of Node.js server code. Generally speaking, things are working fine. However, I can't figure out a way to tell whether an UPDATE statement does not update any rows. For instance, if I have code such as:

connection.query("UPDATE table SET columnA = valA WHERE columnB = valB;",
    function(err, rows, fields) {

   ..some code..
}

As far as I can tell, none of the callbacks (err, rows, fields) will provide me with any information informing me that zero rows were affected. This is important information to me. How can I resolve this? Thanks!

• javascript
• mysql
• node.js

1 Answer 1

I assume you're using node-mysql. The count of changed rows is in result.changedRows variable.

Try:

connection.query('UPDATE table SET ...', function (err, result) {
  if (err) throw err;
  console.log('changed ' + result.changedRows + ' rows');
});

You can also get result.affectedRows.

Further info is within the docs.