I try to connect to Azure SQL with:
import java.sql.*;
public class ExampleJTDS {
public static void main(String[] args) {
// Setting.
String connectionUrl = "jdbc:jtds:sqlserver://SERVER.database.windows.net:1433/DATABASE;ssl=off";
String user = "USER#SERVER";
String pass = "PASSWORD";
// Declare the JDBC object.
Connection conn = null;
try {
// Establish the connection.
Class.forName("net.sourceforge.jtds.jdbc.Driver");
conn = DriverManager.getConnection(connectionUrl, user, pass);
}
catch (Exception e) {
e.printStackTrace();
}
}
}
But I am getting:
java.sql.SQLException: I/O Error: DB server closed connection.
at net.sourceforge.jtds.jdbc.TdsCore.nextToken(TdsCore.java:2481)
at net.sourceforge.jtds.jdbc.TdsCore.login(TdsCore.java:632)
at net.sourceforge.jtds.jdbc.JtdsConnection.<init>(JtdsConnection.java:371)
at net.sourceforge.jtds.jdbc.Driver.connect(Driver.java:184)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at run.ExampleJTDS.main(ExampleJTDS.java:21)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
If I force the encryption by substituting ssl=off with ssl=require, I am getting:
java.sql.SQLException: Network error IOException: Connection reset
at net.sourceforge.jtds.jdbc.JtdsConnection.<init>(JtdsConnection.java:436)
at net.sourceforge.jtds.jdbc.Driver.connect(Driver.java:184)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:247)
at run.ExampleJTDS.main(ExampleJTDS.java:21)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Interestingly, I can connect to the database from the same computer and with the same JDBC driver with SQuirreL SQL (although without SSL - SQuirreL SQL manages to put the credentials into the first TDS packet and Azure accepts that). Hence, the problem should not be in the setting of firewalls.
Metadata:
Server: Azure V12
Driver: jtds-1.3.1
JRE: 1.8.0_72-b15 (from Oracle)
_JAVA_OPTIONS: -Djsse.enableCBCProtection=false
security.provider.1: sun.security.provider.Sun
OS: OS X 10.11.5
SQuirreL SQL: 3.7.1
How can I connect to Azure SQL from Java?
Per my experience, I think the issue was caused by the connection string which is the variable connectionUrl of your code. I have answered your similar question of the SO thread, please see How to connect to Azure SQL with JDBC.
However, using jTDS instead of Microsoft JDBC driver for SQL Server has a little difference, you can refer to a note in the step 3 of the tutorial to know it. As reference, I post the contento of the note here.
Note:
If you are using the JTDS JDBC driver, then you will need to add "ssl=require" to the URL of the connection string and you need to set the following option for the JVM "-Djsse.enableCBCProtection=false". This JVM option disables a fix for a security vulnerability, so make sure you understand what risk is involved before setting this option.
Hope it helps. Any concern, please feel free to let me know.
Related
I have the following use-case:
I have a system that needs to use two different connection pools, One is for 'local' database (Meaning a database running on the local machine) and the other one is a 'remote' database. (Meaning a database that is running on a remote different server)
The remote database is a configuration sharing database, while the local one is has different kinds of data.
I've created two classes in order to connect to those datababase:
public class ConnectionPool {
private static BasicDataSource ds = createNewDatasource();
private static BasicDataSource createNewDatasource() {
BasicDataSource ds = new BasicDataSource();
String url = "jdbc:mysql://127.0.0.1:3306/SOME_DB"
ds.setUrl(url);
ds.setUsername(...);
ds.setPassword(...);
return ds;
}
public static Connection getConnection() throws SQLException {
return ds.getConnection();
}
}
The other class looks exactly the same, Only it's called RemoteConnection and the url is changed to:
String url = "jdbc:mysql://<REMOTE_IP>:3306/SOME_DB_2"
Running the above classes, I keep receiving the following message in my logs:
ERROR (RemoteConnection.java:40) - Failed on getConnection
java.sql.SQLException: Cannot create PoolableConnectionFactory (Access denied for user '...'#'<MACHINE_LOCAL_IP>' (using password: YES))
at org.apache.commons.dbcp2.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:2291)
at org.apache.commons.dbcp2.BasicDataSource.createDataSource(BasicDataSource.java:2038)
at org.apache.commons.dbcp2.BasicDataSource.getConnection(BasicDataSource.java:1533)
at Censored.RemoteConnection.getConnection(RemoteConnection.java:59)
...
Caused by: java.sql.SQLException: Access denied for user '...'#'<MACHINE_LOCAL_IP>' (using password: YES)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:965)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3973)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3909)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:873)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1710)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1226)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2188)
at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2219)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2014)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:776)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.GeneratedConstructorAccessor31.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:57)
at java.lang.reflect.Constructor.newInstance(Constructor.java:437)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:386)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:330)
at org.apache.commons.dbcp2.DriverConnectionFactory.createConnection(DriverConnectionFactory.java:39)
at org.apache.commons.dbcp2.PoolableConnectionFactory.makeObject(PoolableConnectionFactory.java:256)
at org.apache.commons.dbcp2.BasicDataSource.validateConnectionFactory(BasicDataSource.java:2301)
at org.apache.commons.dbcp2.BasicDataSource.createPoolableConnectionFactory(BasicDataSource.java:2287)
...
Firstly, The error above is weird. I've never used the machine local IP. So I don't understand where it came from. In addition, It doesn't seems like a privilege problem since I've tried logging into remote database through cli, using:
mysql -u'...' -p'...' -h <REMOTE_IP> SOME_DB_2
And it connected successfully. It smells to me like a JDBC Driver or connection definition problem but I can't seem to find the problematic spot.
Any idea what I'm doing wrong?
I've found the problem. It was an SSL issue.
The user I've used had to connect with SSL certificate.
That's also the reason why I've seen the local machine IP in the error.
A way to check is:
Select * from mysql.user where user='...';
What I've found was that:
ssl_type != ''
So I had to define:
jdbc:mysql://<REMOTE_IP>:3306/SOME_DB_2&useSSL=true
Configure the relevant certificates, and all was well.
I have a MySQL database. My friend is trying to access it from a different computer using my public IP.
This is the program he used to test the connection:
public class Main {
public static void main(String args[]) {
String url = "jdbc:mysql://IPadresss:3307/javabase";
String username = "bob";
String password = "bob";
Properties properties = new Properties();
properties.setProperty("bob", "bob");
properties.setProperty("bob", "bob");
properties.setProperty("useSSL", "false");
properties.setProperty("autoReconnect", "true");
System.out.println("Connecting database...");
try (Connection connection = DriverManager.getConnection(url, properties)) {
System.out.println("Database connected!");
} catch (SQLException e) {
throw new IllegalStateException("Cannot connect the database!", e);
}
}
}
This is the error my friend, who is the client, gets:
Connecting database...
Exception in thread "main" java.lang.IllegalStateException: Cannot connect the database!
at SQLConnector.Main.main(Main.java:23)
Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: Could not create connection to database server. Attempted reconnect 3 times. Giving up.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.Util.getInstance(Util.java:408)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:918)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:897)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:886)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:860)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2163)
at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2088)
at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:806)
at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:425)
at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:410)
at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:328)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:208)
at SQLConnector.Main.main(Main.java:20)
Caused by: java.sql.SQLException: Access denied for user ''#'Freinds ip' (using password: NO)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:964)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3970)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:3906)
at com.mysql.jdbc.MysqlIO.checkErrorPacket(MysqlIO.java:873)
at com.mysql.jdbc.MysqlIO.proceedHandshakeWithPluggableAuthentication(MysqlIO.java:1710)
at com.mysql.jdbc.MysqlIO.doHandshake(MysqlIO.java:1226)
at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2253)
at com.mysql.jdbc.ConnectionImpl.connectWithRetries(ConnectionImpl.java:2104)
... 13 more
Please help me find out what is wrong with my method of connecting to the server, I have remotely given privileges to my friend (user "bob").
So, you have the following error:
com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure java.net.ConnectException: Connection
refused
This could happen for a variety of reasons, and I'm quoting from this answer
If you get a SQLException: Connection refused or Connection timed out
or a MySQL specific CommunicationsException: Communications link
failure, then it means that the DB isn't reachable at all.
This can have one or more of the following causes:
IP address or hostname in JDBC URL is wrong.
Hostname in JDBC URL is not recognized by local DNS server.
Port number is missing or wrong in JDBC URL. [Assuming the one you mentioned is correct]
DB server is down.
DB server doesn't accept TCP/IP connections.
DB server has run out of connections.
Something in between Java and DB is blocking connections, e.g. a firewall or proxy.
To solve the one or the other, follow the following advice:
Verify and test them with ping.
Refresh DNS or use IP address in JDBC URL instead.
Verify it based on my.cnf of MySQL DB.
Start the DB.
Verify if mysqld is started without the --skip-networking option.
Restart the DB and fix your code accordingly that it closes connections in finally.
Disable firewall and/or configure
firewall/proxy to allow/forward the port.
This question already has answers here:
SqlServer: Login failed for user
(14 answers)
Closed 4 years ago.
I am simply trying to test my connection with SQL Server 2008 as follows:
public class ForJDBC {
public static void main(String[] args) {
try{
Connection conn = DriverManager.getConnection("jdbc:sqlserver://XX.XX.X.XXX:1433;databaseName=MyDB;user=sa;password=mypassword");
if(conn != null){
System.out.println("Connection is Successfull");
}
}
catch(SQLException ex){
ex.printStackTrace();
}
}
}
But I keep on getting the following exception:
com.microsoft.sqlserver.jdbc.SQLServerException: Login failed for user 'sa'. ClientConnectionId:96f7d048-9734-4fd8-8216-21231d89b2e6
at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:216)
at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:216)
at com.microsoft.sqlserver.jdbc.TDSTokenHandler.onEOF(tdsparser.java:254)
at com.microsoft.sqlserver.jdbc.TDSParser.parse(tdsparser.java:84)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.sendLogon(SQLServerConnection.java:2908)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.logon(SQLServerConnection.java:2234)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.access$000(SQLServerConnection.java:41)
at com.microsoft.sqlserver.jdbc.SQLServerConnection$LogonCommand.doExecute(SQLServerConnection.java:2220)
at com.microsoft.sqlserver.jdbc.TDSCommand.execute(IOBuffer.java:5696)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(SQLServerConnection.java:1715)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.connectHelper(SQLServerConnection.java:1326)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.login(SQLServerConnection.java:991)
at com.microsoft.sqlserver.jdbc.SQLServerConnection.connect(SQLServerConnection.java:827)
at com.microsoft.sqlserver.jdbc.SQLServerDriver.connect(SQLServerDriver.java:1012)
at java.sql.DriverManager.getConnection(DriverManager.java:664)
at java.sql.DriverManager.getConnection(DriverManager.java:270)
at forjdbc.ForJDBC.main(ForJDBC.java:35)
When I connect to MySQL 5.5, it works fine.
Troubleshooting Steps I have followed:
1) Tried Logging with the "sa" user name and password within the SQL Server Management Console
using SQL Server Management studio
2) I have sqljdbc4.jar in my Source Package folder of Netbeans 7.4
3) Updated to Java 8
Please let me know what am I doing wrong and let me know if I can answer any questions.
Connection String Problem...
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
Connection connection = DriverManager
.getConnection("jdbc:sqlserver://localhost:1433;\SQLEXPRESS;databaseName=Tema6","sa","123456")
I think you missed loading the Driver class and registering it.
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
If still it is not working then please ensure your SQLServer services is running
Click SQL --> click right mouse --> propretise --> Securiti -->tick SQL server and windows Authentication mode
90% success!
I want to connect both Oracle and DB2 databases for some reason using JDBC. In main class when I try to connect Oracle, Connection is successfull but DB2 connection is NOT successfull giving this error: "Yuva acilirken hata olustu" means "Socket can not be opened" . What can be the problem??? Oracle works but DB2 does not work. I checked all password, usernames, host names and ports again and again for DB2.
COM.ibm.db2.jdbc.DB2Exception: [IBM][JDBC Driver] CLI0616E Yuva açılırken hata oluştu. SQLSTATE=08S01
at COM.ibm.db2.jdbc.net.SQLExceptionGenerator.socketException(Unknown Source)
at COM.ibm.db2.jdbc.net.DB2Connection.create(Unknown Source)
at COM.ibm.db2.jdbc.net.DB2Connection.<init>(Unknown Source)
at COM.ibm.db2.jdbc.net.DB2Driver.connect(Unknown Source)
at java.sql.DriverManager.getConnection(DriverManager.java:590)
at java.sql.DriverManager.getConnection(DriverManager.java:232)
To get connection, I write these in main,
connORA = DirectConnection.getOracleConnection();
connDB2 = DirectConnection.getDB2Connection();
My Connection Class I defined Oracle COnnection and DB2 connection as follows: (Maybe there is a problem in DB2 Connection Method? Oracle connects succesfully)
public static Connection getOracleConnection() throws SQLException, ClassNotFoundException{
return getConnection("oracle.jdbc.driver.OracleDriver", "jdbc:oracle:thin:#host:port:name", "username", "password");}
public static Connection getDB2Connection() throws SQLException{
return getConnection("COM.ibm.db2.jdbc.net.DB2Driver", "jdbc:db2://host:port:name","username", "password");}
Firstly, as #ThePhantom05 mentioned, you should be using the JCC driver, not the older net driver. The correct URL pattern for a DB2 JDBC connection will be jdbc:db2://host:port/database_name
Try using this as your driver instead:
String driver = "com.ibm.db2.jcc.DB2Driver";
my sql server instance name is MYPC\SQLEXPRESS and I'm trying to create a jTDS connection string to connect to the database 'Blog'. Can anyone please help me accomplish that?
I'm trying to do like this:
DriverManager.getConnection("jdbc:jtds:sqlserver://127.0.0.1:1433/Blog", "user", "password");
and I get this:
java.sql.SQLException: Network error IOException: Connection refused: connect
at net.sourceforge.jtds.jdbc.ConnectionJDBC2.<init>(ConnectionJDBC2.java:395)
at net.sourceforge.jtds.jdbc.ConnectionJDBC3.<init>(ConnectionJDBC3.java:50)
at net.sourceforge.jtds.jdbc.Driver.connect(Driver.java:184)
at java.sql.DriverManager.getConnection(Unknown Source)
at java.sql.DriverManager.getConnection(Unknown Source)
at SqlConnection.Connect(SqlConnection.java:19)
at main.main(main.java:11)
Caused by: java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(Unknown Source)
at java.net.PlainSocketImpl.connectToAddress(Unknown Source)
at java.net.PlainSocketImpl.connect(Unknown Source)
at java.net.SocksSocketImpl.connect(Unknown Source)
at java.net.Socket.connect(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at net.sourceforge.jtds.jdbc.SharedSocket.createSocketForJDBC3(SharedSocket.java:305)
at net.sourceforge.jtds.jdbc.SharedSocket.<init>(SharedSocket.java:255)
at net.sourceforge.jtds.jdbc.ConnectionJDBC2.<init>(ConnectionJDBC2.java:323)
... 6 more
As detailed in the jTDS Frequenlty Asked Questions, the URL format for jTDS is:
jdbc:jtds:<server_type>://<server>[:<port>][/<database>][;<property>=<value>[;...]]
So, to connect to a database called "Blog" hosted by a MS SQL Server running on MYPC, you may end up with something like this:
jdbc:jtds:sqlserver://MYPC:1433/Blog;instance=SQLEXPRESS;user=sa;password=s3cr3t
Or, if you prefer to use getConnection(url, "sa", "s3cr3t"):
jdbc:jtds:sqlserver://MYPC:1433/Blog;instance=SQLEXPRESS
EDIT: Regarding your Connection refused error, double check that you're running SQL Server on port 1433, that the service is running and that you don't have a firewall blocking incoming connections.
Really, really, really check if the TCP/IP protocol is enabled in your local SQLEXPRESS instance.
Follow these steps to make sure:
Open "Sql Server Configuration Manager" in "Start Menu\Programs\Microsoft SQL Server 2012\Configuration Tools\"
Expand "SQL Server Network Configuration"
Go in "Protocols for SQLEXPRESS"
Enable TCP/IP
If you have any problem, check this blog post for details, as it contains screenshots and much more info.
Also check if the "SQL Server Browser" windows service is activated and running:
Go to Control Panel -> Administrative Tools -> Services
Open "SQL Server Browser" service and enable it (make it manual or automatic, depends on your needs)
Start it.
That's it.
After I installed a fresh local SQLExpress, all I had to do was to enable TCP/IP and start the SQL Server Browser service.
Below a code I use to test the SQLEXPRESS local connection. Of course, you should change the IP, DatabaseName and user/password as needed.:
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
public class JtdsSqlExpressInstanceConnect {
public static void main(String[] args) throws SQLException {
Connection conn = null;
ResultSet rs = null;
String url = "jdbc:jtds:sqlserver://127.0.0.1;instance=SQLEXPRESS;DatabaseName=master";
String driver = "net.sourceforge.jtds.jdbc.Driver";
String userName = "user";
String password = "password";
try {
Class.forName(driver);
conn = DriverManager.getConnection(url, userName, password);
System.out.println("Connected to the database!!! Getting table list...");
DatabaseMetaData dbm = conn.getMetaData();
rs = dbm.getTables(null, null, "%", new String[] { "TABLE" });
while (rs.next()) { System.out.println(rs.getString("TABLE_NAME")); }
} catch (Exception e) {
e.printStackTrace();
} finally {
conn.close();
rs.close();
}
}
}
And if you use Maven, add this to your pom.xml:
<dependency>
<groupId>net.sourceforge.jtds</groupId>
<artifactId>jtds</artifactId>
<version>1.2.4</version>
</dependency>
jdbc:jtds:sqlserver://x.x.x.x/database replacing x.x.x.x with the IP or hostname of your SQL Server machine.
jdbc:jtds:sqlserver://MYPC/Blog;instance=SQLEXPRESS
or
jdbc:jtds:sqlserver://MYPC:1433/Blog;instance=SQLEXPRESS
If you are wanting to set the username and password in the connection string too instead of against a connection object separately:
jdbc:jtds:sqlserver://MYPC/Blog;instance=SQLEXPRESS;user=foo;password=bar
(Updated my incorrect information and add reference to the instance syntax)
A shot in the dark, but
From the looks of your error message, it seems that either the sqlserver instance is not running on port 1433 or something is blocking the requests to that port
SQLServer runs the default instance over port 1433. If you specify the port as port 1433, SQLServer will only look for the default instance. The name of the default instance was created at setup and usually is SQLEXPRESSxxx_xx_ENU.
The instance name also matches the folder name created in Program Files -> Microsoft SQL Server. So if you look there and see one folder named SQLEXPRESSxxx_xx_ENU it is the default instance.
Folders named MSSQL12.myInstanceName (for SQLServer 2012) are named instances in SQL Server and are not accessed via port 1433.
So if your program is accessing a default instance in the database, specify port 1433, and you may not need to specify the instance name.
If your program is accessing a named instance (not the default instance) in the database DO NOT specify the port but you must specify the instance name.
I hope this clarifies some of the confusion emanating from the errors above.