Node.jsMySQL Update
Update Table
You can update existing records in a table by using the "UPDATE" statement:
Example
Overwrite the address column from "Valley 345" to "Canyon 123":
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");
});
});
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:
Run "demo_db_update.js"
Which will give you this result:
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
Return the number of affected rows:
Which will produce this result:
