Node.js MySQL Delete — Node.js interactive lesson

Delete Record

You can delete records from an existing table by using the "DELETE FROM" statement:

Example

Delete any record with the address "Mountain 21":

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 = "DELETE FROM customers WHERE address = 'Mountain 21'";
 con.query( sql, function (err, result) {
 if (err) throw err;
 console.log("Number of records deleted: " + result.affectedRows);
 });
});

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

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

Run "demo_db_delete.js"

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

Which will give you this result

Number of records deleted: 1

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: '', protocol41: true,
 changedRows: 0
}

The values of the properties can be displayed like this:

Return the number of affected rows

console.log(result.affectedRows)

Which will produce this result