Develop Reference

Unable to connect to a Oracle db from Linux machine in java

I have registered a Linux machine as runner in my gitlab and tried to execute my scripts there.
While executing I got an error for database connection
Issue : java.sql.SQLRecoverableException: IO Error: The Network Adapter could not establish the connection
When I connect from my local machine (Windows 7 & 10) it is working fine.
Attempts:
Tried to connect using jtds but I'm getting some other unknown issue.
Checked few other answers and they have provided that it could be because of firewall enabled but since we did not have full access to that db server , I could not disable and check.(Could this be the issue?)
My Connection code :
ConURL = "jdbc:oracle:thin:#" + ConstructSQLConnectionURL(host,sid,port);
Class.forName("oracle.jdbc.driver.OracleDriver");
con = DriverManager.getConnection(ConURL, dbUserName, dbPassword);
I am stuck with this issue and blocked from executing pipeline.
Can anyone let me know what could be the possible reason for this and help me with this?
Thanks in advance

It appears to be a network connectivity issue. I'd start with local firewalls on each system. Can you ping the database from the client? If not, look for network routing or firewall blockers. Also look at host-based firewalls, or confirm with the DBA whether there is something like valid node checking in place to limit database clients.

Unable to connect Java application to SQL Server database

I am trying to write a Java desktop app that can connect to my database made with Microsoft SQL Server Manager to allow me to view and update it. But, I am having trouble getting the connection to work. I've read through a bunch of tutorials and threads here on Stack Exchange of similar problems, and I'm not sure what I'm doing wrong.
The server is called "SQLEXPRESS" using Windows authentication. I downloaded the JDBC driver found here: https://www.microsoft.com/en-us/download/details.aspx?displaylang=en&id=11774 installed it in NetBeans by going to "Services-Databases(right click)-New Connection-Add", but I also added it as a library in my project.
When I try this code, I get the exception that the TCP/IP connection failed either because the server isn't running or port 1433 is locked:
try{
String
URL="jdbc:sqlserver://sqlexpress:1433;DatabaseName=GreenhouseManagement";
Connection conn = DriverManager.getConnection(URL,"","");
System.out.println("connected");
}catch(Exception e){
System.out.println("Oops\n"+e);
}
What do I need to change to fix this?

You might need to reconfigure your connection string into this format.
jdbc:microsoft:sqlserver://HOST:1433;DatabaseName=DATABASE
HOST in this case is most likely to be "localhost" since you are connecting on a local machine.
DATABASE will be the name of your database
Reference: http://alvinalexander.com/java/jdbc-connection-string-mysql-postgresql-sqlserver

Unable to get SQL Server connection object

I wrote a simple code to connect to SQL Server database and to does a simple select statement, this code runs successfully on my local machine over VPN but when I deploy the same code in the servers, then my code is stopping at getting the DB connection object.
It is not even throwing any timeout exception, so I thought of a port issue and checked using telnet which is successful. Can anyone please suggest why this might happen? I am able to get connection object of the same DB from my local machine over VPN.
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
String connectionUrl = props.getProperty("DBURI");
Connection conn=null;
System.out.println(connectionUrl.trim());
conn = DriverManager.getConnection(connectionUrl.trim());

Problem with the sqljdbc jar file , Used any 32 bit one , After replacing the jar , everything worked fine. Thanks

Connecting to external database through telnet

I have a java program that connects to a MS SQL database. The program works perfectly when running through eclipse however I get an error when I run it through AIX:
java.sql.SQLException: Network error IOException: A remote host refused an attempted connect operation.
I can successfully ping the server but am not able to telnet into the server. I am also not able to telnet from my windows desktop.
I am using jtds to connect:
String connectionString = "jdbc:jtds:sqlserver://"+dropez_ip_address+"/"+dropez_db_name;
ResultSet rs = null;
Statement stmt = null;
try{
Class.forName("net.sourceforge.jtds.jdbc.Driver");
Connection conn = DriverManager.getConnection(connectionString, dropez_db_username, dropez_db_password);
stmt = conn.createStatement();
}catch(Exception e){}
Here is some documentation from jTDS regarding the issue, but I am still not able to resolve the issue.
Why do I get java.sql.SQLException: "Network error IOException: Connection refused: connect" when trying to get a connection?
The "Connection refused" exception is thrown by jTDS when it is unable to connect to the server. There may be a number of reasons why this could happen:
- The server name is misspelled or the port number is incorrect.
- SQL Server is not configured to use TCP/IP. Either enable TCP/IP from SQL Server's Network Utility app or have jTDS connect via named pipes (see the URL format for information on how to do this).
- There is a firewall blocking port 1433 on the server.
To check whether TCP/IP is enabled and the port is not blocked you can use "telnet 1433". Until telnet doesn't connect, jTDS won't either. If you can't figure out why, ask your network administrator for help.

If you can't telnet on port 1433, you are blocked by a firewall somewhere in the middle between your machine and the server. That's not a java related problem.
May it be that when you say "it runs perfectly under eclipse but not AIX" you are taking about 2 different computers ? If so, the one with eclipse is not firewalled, the one where you deploy your app is blocked.
But again, nothing to do with java. It's a level 3 error (TCP layer) of TCP-IP model.
Regards,
Stéphane

Your SQL Server database probably doesn't have the TCP/IP protocol enabled, to enable it:
From the Microsoft SQL Server 2005 -> Configuration Tools, open the 'Microsoft SQL Server Configuration Manager'.
Expand ‘SQL Server 2005 Network Configuration’, and then click ‘Protocols for ’.
Right-click ‘TCP/IP’ and then click ‘Enable’. The icon for the protocol will change to show that the protocol is enabled.
For SQL Server 2008:

Connecting to hosted MySQL server with Java

I've been recently trying to connect to a hosted MySQL using Java but can't get it to work. I can connect to a local MySQL with localhost using:
connect = DriverManager.getConnection("jdbc:mysql://localhost/lego?"
+ "user=******&password=*******");
(Replacing the astrisks withmy username and password)
I can connect to the hosted MySQL database fine with PHP using:
mysql_connect('mysql.hosts.co.uk','******','**********');
mysql_select_db('test');
My problem is, I cannot connect via Java. I have an Exception which is caught if the connection doesn't work and this is always printed out.
Any ideas why it isn't working? Am I doing something wrong?
Thanks for your time,
InfinitiFizz

since it works in php (i guess you didn't try to connect from a local place with php???) it shouldn't be a port problem... but you should check that port 3306 is open... and ask the hosts company about that.
Have you noticed that in the DriverManager
http://java.sun.com/javase/6/docs/api/java/sql/DriverManager.html
you have:
getConnection(String url)
but also:
getConnection(String url, String user, String password)
Perhaps it would work better...

My guess is that you need to select a non-standard port, since I'd imagine the hosting server is serving lots of MySQL instances and they can't all use the normal one. I don't see selection of a port here.
If that's not it, perhaps there is a firewall issue somewhere along the way that's blocking the port or connection.