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Node.js MySQL Result Object

When executing a MySQL query in Node.js, an object named Result Object is returned to the callback function. The result object contains a result set or properties that provide information about the execution of the query on the MySQL Server.

Node.js MySQL result object

The content of the result object depends on the SQL query performed on the MySQL Server. The table below describes the result object of the query, such as select, insert, update, and delete.

MySQL queryResult object
SELECT FROMResult set containing records
INSERT INTOObject containing the execution state
UPDATEObject containing the execution state
DELETE FROM

Object containing the execution state

With the help of the following examples, we will understand how to access the properties of the records in the result set and how to access the properties of the execution state.

  • MySQL SELECT FROM query – Access ResultSet

  • MySQL INSERT INTO query – Access the properties of the result object

  • MySQL UPDATE query-Access the properties of the result object

  • MySQL DELETE FROM query-Access the properties of the result object

Example – MySQL SELECT FROM query – Access ResultSet

We can use the dot (.) operator to access the records in the result set as an array and as properties of the record.

//　Node.js MySQL result object example
//　Import the mysql module
var mysql = require('mysql');　
　
//　Create a connection variable with the required details
var con = mysql.createConnection({　
　　host: "localhost",　//　IP address of the server running MySQL
　　user: "arjun",　//　MySQL database username
　　password: "password",　//　The corresponding password
　　database: "studentsDB"　//　Use the specified database
　});　
　
//　Establish a connection with the database
con.connect(function(err) {　
　　if (err) throw err;　
　　//　If the connection is successful
　　con.query("SELECT　*　FROM students", function err, result, fields) {　
　　　　//　If any error occurs during the execution of the above query, throw an error
　　　　if (err) throw err;　
　　　　//　If there is no error, you will get the result
　　　　//　Iterate over all rows in the result
　　　　Object.keys(result).forEach(function(key) {　
　　　　　　var row = result[key];　
　　　　　　console.log(row.name)　
　　　　});　
　　});　
　});

Run the above program using the node in the terminal

Terminal Output

arjun@arjun-VPCEH26EN:~/workspace/nodejs$ node selectUseResultObject.js　
John
Arjun
Prasanth
Adarsh
Raja
Sai
Ross
Monica
Lee
Bruce
Sukumar

Example – MySQL INSERT INTO query

We can use the DOT (.) operator to access the properties of the result object.

//　Import the mysql module
var mysql = require('mysql');　
　
//　Create a connection variable with the required details
var con = mysql.createConnection({　
　　host: "localhost",　//　IP address of the server running MySQL
　　user: "arjun",　//　MySQL database username
　　password: "password",　//　The corresponding password
　　database: "studentsDB"　//　Use the specified database
　});　
　
//　Establish a connection with the database
con.connect(function(err) {　
　　if (err) throw err;　
　　//　If the connection is successful
　　var records = [　
　　　　['Jack',　16,　82],　
　　　　['Priya',　17,　88],　
　　　　['Amy',　15,　74);　
　　);　
　　con.query("INSERT INTO students (name,rollno,marks) VALUES ?", [records], function(err, result, fields) {　
　　　　//　If any error occurs during the execution of the above query, throw an error
　　　　if (err) throw err;　
　　　　//　If there is no error, you will get the result
　　　　console.log(result);　
　　　　console.log("Number of rows affected : ",　+　result.affectedRows);　
　　　　console.log("Number of records affected with warning : ",　+　result.warningCount);　
　　　　console.log("Message from MySQL Server : ",　+　result.message);　
　　});　
　});

Run the above program using the node in the terminal

Terminal Output

arjun@arjun-VPCEH26EN:~/workspace/nodejs$ node MultipleInsertExample.js　
OkPacket {　
　　fieldCount: 0,　
　　affectedRows:　3,　
　　insertId: 0,　
　　serverStatus:　2,　
　　warningCount: 0,　
　　message: '&Records:　3　　Duplicates: 0    Warnings: 0',　
　　protocol41: true,　
　　changedRows: 0 }　
Number of rows affected :　3
Number of records affected with warning : 0
Message from MySQL Server: &Records:　3　Duplicates: 0 Warnings: 0

Example – MySQL UPDATE query

We can use the DOT (.) operator to access the properties of the result object.

//　Import the mysql module
var mysql = require('mysql');　
　
//　Create a connection variable with the required details
var con = mysql.createConnection({　
　　host: "localhost",　//　IP address of the server running MySQL
　　user: "arjun",　//　MySQL database username
　　password: "password",　//　The corresponding password
　　database: "studentsDB"　//　Use the specified database
　});　
　
//　Establish a connection with the database
con.connect(function(err) {　
　　if (err) throw err;　
　　//　If the connection is successful
　　con.query("UPDATE students SET marks=84　WHERE marks=74", function (err, result, fields) {　
　　　　//　If any error occurs during the execution of the above query, throw an error
　　　　if (err) throw err;　
　　　　//　If there is no error, you will get the result
　　　　console.log(result);　
　　　　console.log("Number of rows affected : ",　+　result.affectedRows);　
　　　　console.log("Number of records affected with warning : ",　+　result.warningCount);　
　　　　console.log("Message from MySQL Server : ",　+　result.message);　
　　});　
　});

Run the above program using the node in the terminal

Terminal Output

arjun@arjun-VPCEH26EN:~/workspace/nodejs$ node UpdateRecordsFiltered.js　
OkPacket {　
　　fieldCount: 0,　
　　affectedRows:　3,　
　　insertId: 0,　
　　serverStatus:　34,　
　　warningCount: 0,　
　　message: '(Rows matched:　3　　Changed:　3　　Warnings: 0',　
　　protocol41: true,　
　　changedRows:　3　}　
Number of rows affected :　3
Number of records affected with warning : 0
Message from MySQL Server: (Rows matched:　3　Changed:　3　Warnings: 0

Example – MySQL delete from query

We can use the DOT (.) operator to access the properties of the result object.

//　Import the mysql module
var mysql = require('mysql');　
　
//　Create a connection variable with the required details
var con = mysql.createConnection({　
　　host: "localhost",　//　IP address of the server running MySQL
　　user: "arjun",　//　MySQL database username
　　password: "password",　//　The corresponding password
　　database: "studentsDB"　//　Use the specified database
　});　
　
//　Connect to the database.
con.connect(function(err) {　
　　if (err) throw err;　
　　//　If the connection is successful
　　con.query("DELETE FROM students WHERE rollno>10", function (err, result, fields) {　
　　　　//　If any error occurs during the execution of the above query, throw an error
　　　　if (err) throw err;　
　　　　//　If there is no error, you will get the result
　　　　console.log(result);　
　　　　console.log("Number of rows affected : ",　+　result.affectedRows);　
　　　　console.log("Number of records affected with warning : ",　+　result.warningCount);　
　　　　console.log("Message from MySQL Server : ",　+　result.message);　
　　});　
　});

Run the above program using the node in the terminal

Terminal Output

arjun@arjun-VPCEH26EN:~/workspace/nodejs$ node deleteRecordsFiltered.js　
OkPacket {　
　　fieldCount: 0,　
　　affectedRows:　6,　
　　insertId: 0,　
　　serverStatus:　34,　
　　warningCount: 0,　
　　message: '',　
　　protocol41: true,　
　　changedRows: 0 }　
Number of rows affected :　6
Number of records affected with warning : 0
Message from MySQL Server :

Conclusion

In this Node.js tutorial – Node.js MySQL – we learned how to access the records of the result set and accessed the properties of the result object containing information about the query execution through examples.

Node.js Example大全Node.js MySQL DELETE