MySQL Update

Update Table

You can update existing records in a table by using the "UPDATE" statement:

Example

let mysql = require('mysql');

let con = mysql.createConnection({

host: "localhost",
  user: "yourusername",

password: "yourpassword",
  database: "mydb"
});

con.connect(function(err) {
  if (err) throw err;

let sql = "UPDATE customers SET address = 'Canyon 123' WHERE address =
'Valley 345'";

con.query(sql, function (err, result) {

if (err) throw err;
    console.log(result.affectedRows + "
record(s) updated");
  });
});

Note: Notice the WHERE clause in the UPDATE syntax: The WHERE clause specifies which record or records that should be updated. If you omit the WHERE clause, all records will be updated!

Save the code above in a file called "demo_db_update.js" and run the file:

C:\Users\Your Name>node demo_db_update.js

Which will give you this result:

1 record(s) updated

The Result Object

When executing a query, a result object is returned.

The result object contains information about how the query affected the table.

The result object returned from the example above looks like this:

{
  fieldCount: 0,
  affectedRows: 1,
  insertId: 0,

serverStatus: 34,
  warningCount: 0,
  message: '(Rows
matched: 1 Changed: 1 Warnings: 0',
  protocol41: true,

changedRows: 1
}

The values of the properties can be displayed like this:

Example

console.log(result.affectedRows)

Which will produce this result:

1