Connecting to MS SQL DB from Java thows error

Question

I have MS SQL running on my Mac, installed and configured over Docker - As instructed in - https://www.devart.com/dbforge/sql/studio/install-sql-server-on-mac.html.

Below is my code, which I tried to connect to the Database. The server is up and running.

But I get the mentioned error, and I am not sure what is the exact problem:

import java.sql.*;
import javax.swing.*;

public class DBConnectTrial1 {
  public static void main(String[] args) {
    // TODO Auto-generated method stub
    try {
      String driver = "com.mysql.jdbc.Driver";
      String url =
          "jdbc:mysql://localhost:3306/mssql_trial?enabledTLSProtocols=TLSv1.2";
      String username = "sa";
      String password = "DB_Password";

      Class.forName(driver);

      Connection conn = DriverManager.getConnection(url, username, password);
      // return conn;

      // JOptionPane.showMessageDialog(null, "Connected to the database");

      System.out.println("Connection established");
    }

    catch (Exception e) {
      // JOptionPane.showMessageDialog(null, "Could not connect to the
      // database...");

      // return null;
      e.printStackTrace();
    }
  }
}

Exception :

com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at java.base/jdk.internal.reflect.DirectConstructorHandleAccessor.newInstance(DirectConstructorHandleAccessor.java:62)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:502)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:486)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1121)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:357)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2479)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2516)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2301)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:834)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
    at java.base/jdk.internal.reflect.DirectConstructorHandleAccessor.newInstance(DirectConstructorHandleAccessor.java:62)
    at java.base/java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:502)
    at java.base/java.lang.reflect.Constructor.newInstance(Constructor.java:486)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:416)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:346)
    at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:683)
    at java.sql/java.sql.DriverManager.getConnection(DriverManager.java:230)
    at DBConnectTrial1.main(DBConnectTrial1.java:19)
Caused by: java.net.ConnectException: Connection refused
    at java.base/sun.nio.ch.Net.connect0(Native Method)
    at java.base/sun.nio.ch.Net.connect(Net.java:589)
    at java.base/sun.nio.ch.Net.connect(Net.java:578)
    at java.base/sun.nio.ch.NioSocketImpl.connect(NioSocketImpl.java:583)
    at java.base/java.net.SocksSocketImpl.connect(SocksSocketImpl.java:327)
    at java.base/java.net.Socket.connect(Socket.java:751)
    at java.base/java.net.Socket.connect(Socket.java:686)
    at java.base/java.net.Socket.<init>(Socket.java:555)
    at java.base/java.net.Socket.<init>(Socket.java:356)
    at com.mysql.jdbc.StandardSocketFactory.connect(StandardSocketFactory.java:259)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:307)
    ... 14 more

Can someone please help me to find a solution. I imported the jar file - mysql-connector-java-5.1.25.jar and configured inside the project. I am using eclipse IDE.

Answer 1

Which database brand are you connecting to? You seem to talk about running Microsoft SQL Server, but you are using connection settings for MySQL (now owned by Oracle).

• MySQL's
  • default port is 3306
  • driver is typically com.mysql.jdbc.Driver
• Microsoft SQLServer
  • seem to use a variety of ports, but none 3306 see https://stackoverflow.com/a/49669700/1847378
  • driver is typically com.microsoft.sqlserver.jdbc.SQLServerDriver

Answer 2

Thanks to all who helped me to fix this. Here is the code.

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.Statement;

public class DBConnectTrial1 {

public static void main(String[] args) {


    String  connectionURL = "jdbc:sqlserver://localhost:1433;databaseName=mssql_trial;user=sa;password=DB_Password;encrypt=true;trustServerCertificate=true";
    try {
        System.out.print("Connecting to the server......");
        try (Connection connection = DriverManager.getConnection(connectionURL))   {
            System.out.println("Connected to the Server.");
        }
    }catch (Exception e){
        System.out.println("I am not connected to the Server");
        e.printStackTrace();
    }
}
}