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Java web app can't connect to sql server [duplicate]

I want to connect Java class file with SQL server 2012. I have logged in with SQL server authentication, but I am receiving an error when connecting.
Error:
The TCP/IP connection to the host 127.0.0.1, port 1433 has failed.
Error: "Connection refused: connect. Verify the connection properties.
Make sure that an instance of SQL Server is running on the host and
accepting TCP/IP connections at the port. Make sure that TCP
connections to the port are not blocked by a firewall.".
My code:
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver"); //1. Register your driver
//2. get the connection object
//Connection con = DriverManager.getConnection("jdbc:sqlserver://localhost;databaseName=aysha","sa","admin");
Connection con = DriverManager.getConnection("jdbc:sqlserver://127.0.0.1;databaseName=aysha","user=sa","password=admin");
//"jdbc:sqlserver://127.0.0.1:1433; Instance=SQL2008;" + "databaseName=MB;user=sa;password=123;";
//Connection con = DriverManager.getConnection("jdbc:sqlserver://localhost:1433;databaseName=aysha","sa" , "password");
//3. Prepare a statement
Statement stmt = con.createStatement();
//4. Write the query`
String sql = "Select * from employee";
//5. Execute the statement and
ResultSet rs = stmt.executeQuery(sql);
//6. Process the result set
while (rs.next())
{
System.out.println(rs.getInt(1));
}

Open SQL Server Configuration Manager, and then expand SQL Server 2012 Network Configuration.
Click Protocols for InstanceName, and then make sure TCP/IP is enabled in the right panel and double-click TCP/IP.
On the Protocol tab, notice the value of the Listen All item.
Click the IP Addresses tab:
If the value of Listen All is yes, the TCP/IP port number for this instance of SQL Server 2012 is the value of the TCP Dynamic Ports item under IPAll.
If the value of Listen All is no, the TCP/IP port number for this instance of SQL Server 2012 is the value of the TCP Dynamic Ports item for a specific IP address.
Make sure the TCP Port is 1433.
Click OK.

Easy Solution
Got to Start->All Programs-> Microsoft SQL Server 2012-> Configuration Tool -> Click SQL Server Configuration Manager ->Expand SQL Server Network Configuration-> Protocol ->Enable TCP/IP Right box
Double Click on TCP/IP and go to IP Adresses Tap and Put port 1433 under TCP port.

The error is self explanatory:
Check if your SQL server is actually up and running
Check SQL server hostname, username and password is correct
Check there's no firewall rule blocking TCP connection to port 1433
Check the host is actually reachable
A good check I often use is to use telnet, eg on a windows command prompt run:
telnet 127.0.0.1 1433
If you get a blank screen it indicates network connection established successfully, and it's not a network problem. If you get 'Could not open connection to the host' then this is network problem

Go to Start->All Programs-> Microsoft SQL Server 2012-> Configuration Tool -> Click SQL Server Configuration Manager.
If you see that SQL Server/ SQL Server Browser State is 'stopped'.Right click on SQL Server/SQL Server Browser and click start.
In some cases above state can stop though TCP connection to port 1433 is assigned.

Open %windir%\System32 folder and find SQLServerManagerXX.msc
For example:
C:\Windows\System32\SQLServerManager14.msc
Go to protocols settings then enable TCP/IP port is 1433 by default

As the error says, you need to make sure that your sql server is running and listening on port 1433. If server is running then you need to check whether there is some firewall rule rejecting the connection on port 1433.
Here are the commands that can be useful to troubleshoot:
Use netstat -a to check whether sql server is listening on the desired port
As gerrytan mentioned in answer, you can try to do the telnet on the host and port

important:
after any changes or new settings you must restart SQLSERVER service. run services.msc on Windows

If you are using a named instance, the port you using likely is 1434, instead of 1433, so please check that out using telnet or netstat aforementioned too.

Open Firewall GUI,Open TCP 1433 rule,go to scope tab and add your IP address under Remote IP Address and the problem is solved.

SQLServer - SQLServerException with jdbc access

I have installed on my pc ms sqlserver express 2012, I am trying to reach it via jdbc but I am not successfull, I get the error:
com.microsoft.sqlserver.jdbc.SQLServerException: connection to the host localhost, port 1433 has failed. Error:
"Connection refused: connect. Verify the connection properties.
Make sure that an instance of SQL Server is running on the host
and accepting TCP/IP connections at the port. Make sure that TCP
connections to the port are not blocked by a firewall
I am accessing via the following url: "jdbc:sqlserver://localhost:1433;database=mytest;"
I enabled the tcp/ip via the Sql server configuration manager, but if I run netstat-an I can't see the 1433 port listening.
I disabled windows firewall too...
I am lost :(
Any help?
Thank you!
****UPDATE**
I could overcome the problem by enabling port 1433 on IpAll under Sql Server configuration manager - Sql Server Network configuration - Protocols for SQLEXPRESS - tcp-ip Properties - Ip Addresses. But now I get another error:com.microsoft.sqlserver.jdbc.SQLServerException: Login failed for user 'sa'. ClientConnectionId
Any ideas? thanks!

The answer for the error:
com.microsoft.sqlserver.jdbc.SQLServerException: Login failed for user 'sa'. ClientConnectionId
is:
Go to Object explorer, click on properties (right click on Sql Server name), and on the security tab click on Sql Server and Windows authentication mode.
This worked for me.

Couldn't connect to a MySQL DB via JWS app

Could someone help me with establishing connection with my DB on non-localhost server?
Class.forName("com.mysql.jdbc.Driver");
conn = DriverManager.getConnection("jdbc:mysql://"+SERVER+"/javadb?user=javadb&password=*****");
How could I set-up the SERVER String for my domain www.lmntstudio.cz?
All required files are stored in one folder on the server.
I did it first on my localhost server and everything works well. But with the connection to another server is trouble.

I would recommend not to open MySQL connection from the client/user machine to the server. Because this would make your DB server open and prone to attacks.
Rather consider using web service. call that web service from your JWS application from client side and get the data.
Another point to consider is that opening a connection on a port say 3360 may be blocked by the firewall. If my firewall is set to block any out bound connection on port 3306 the connection could not be established.

Please ensure the MySQL is running in default port 3306 else you need change the port number accordingly.
Connection connection = DriverManager.getConnection(
"jdbc:mysql://www.lmntstudio.cz:3306/javadb", "username", "password");
instead of www.lmntstudio.cz you can use ip of the domain.
run the following in the command line to get the ip
cmd prompt> nslookup www.lmntstudio.cz
The Url syntax as follows
jdbc:mysql://(host/ip):port/databasename", "username", "password"

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:

java to sql server connectivity exception

I have this error/exception-
SQL Exception: com.microsoft.sqlserver.jdbc.SQLServerException: The TCP/IP connection to the host localhost, port 1433 has failed. Error: "connect timed out. Verify the connection properties, check that an instance of SQL Server is running on the host and accepting TCP/IP connections at the port, and that no firewall is blocking TCP connections to the port.".
and my code is-
try {
Class.forName("com.microsoft.sqlserver.jdbc.SQLServerDriver");
String connectionUrl = "jdbc:sqlserver://localhost:1433";
Connection con = DriverManager.getConnection(connectionUrl,"","");
System.out.println("ok");
} catch (SQLException e) {
System.out.println("SQL Exception: "+ e.toString());
}
catch (ClassNotFoundException cE) {
System.out.println("Class Not Found Exception: "+ cE.toString());
}
how can i sovle it,please help me.

This could mean almost anything - basically, it was impossible to connect to port 1433 on localhost. Could be a network problem, could be that the database is not started, could be that it is running but not bound to port 1433.
In a pinch, you can always open a shell and run
telnet localhost 1433
to see if it is possible to make a connection at all.

I had this error.
I fixed it by going into the SQL Server Configuration Manager.
Under SQL Server 2005 Configuration -> Protocols for SQLEXPRESS. Look at the IP Address tab of the Properties of the TCP/IP Protocol.
At the very bottom of the protocol list (under IPALL), the TCP Port field was blank. I put 1433 there, saved, restarted the SQL service and it worked great :)

It's telling you it can't connect.
Check that sql server is available on your local machine on that port.
Check that sql server is accepting connections with the blank name and password you're providing in your getConnection() invocation.
Check that your jdbc url is in the correct form, they're sometimes manufacturer/driver specific.

The error just means that java was not able to connect to your database. Either database is not running or your firewall is blocking connections to it. If you are sure your DB server is up on your localhost, try after disabling your windows firewall.

Lets look at some of the possibilities:
The database server is not listening on localhost:1433 : you probably would get a "connection refused" rather than a "connection timed out"
The database server is catatonic (i.e. in a state where it is not responding to requests) : you could get a "connection timed out".
The database server is massively overloaded : you could get a "connection timed out", but you would probably notice that the machine was very slow.
The local software firewall is configured to block all requests to port 1433 : you could get either "connection refused" or "connection timed out" ... or some other response. (It depends exactly what the firewall does with unwanted traffic.)
The loopback interface (for IP 127.0.0.x) is not configured : you are more likely to get "no route to host" or "no route to network".
The DNS entry for localhost is misconfigured (i.e. localhost doesn't resolve to 127.0.0.x) - lots of things could happen ... depending on how it is misconfigured.
Here are some things you could do to diagnose the problem ... depending on your system:
Look at the configured networks using ipconfig or ifconfig.
Look at "/etc/hosts" to check the entry for localhost
Try to connect to the service using telnet -p 1433
Use "ps" or the task manager to see what processes are running.
Check the local firewall configs to ensure that 1433 is open for (at least) TCP from the configured localhost IP address (probably 127.0.0.1).

I had a problem similar to this, and solved it by adding the line:
System.setProperty("java.net.preferIPv4Stack", "true");
The problem was it used IPv6 instead of IPv4 to access the db host (I used it for a DB on a remote host, not localhost).
Hope it helps.