Connection to database Exception

[ragi singh]

Hi

I am trying to connect to oracle database in my application however i get the following exception
Inside the second try block
java.sql.SQLException: Io exception: The Network Adapter could not establish the connection
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:111)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:145)
at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:254)
at oracle.jdbc.driver.T4CConnection.logon(T4CConnection.java:386)
at oracle.jdbc.driver.PhysicalConnection.<init>(PhysicalConnection.java:413)
at oracle.jdbc.driver.T4CConnection.<init>(T4CConnection.java:164)
at oracle.jdbc.driver.T4CDriverExtension.getConnection(T4CDriverExtension.java:34)
at oracle.jdbc.driver.OracleDriver.connect(OracleDriver.java:752)
at java.sql.DriverManager.getConnection(DriverManager.java:582)
at java.sql.DriverManager.getConnection(DriverManager.java:185)
at Dbconnection.main(Dbconnection.java:17)

and my code is as follows

public class Dbconnection {
public static void main(String[] args){
try{
Class.forName("oracle.jdbc.driver.OracleDriver");
}catch(ClassNotFoundException cne){
}
try{
System.out.println("Inside the second try block");
String url="jdbc:oracle:thin:@localhost:1521:scott";
Connection conn=DriverManager.getConnection(url,"scott","tiger");
Statement stmt=conn.createStatement();
int c=stmt.executeUpdate("insert into students(StudentId,StudentName) values(123,'Tasneem')");
//System.out.println(" The student id is "+rs.getInt(1));
System.out.println("Number of rows updated"+c);
}
catch(ArrayIndexOutOfBoundsException ae){
ae.printStackTrace();
}
catch(SQLException sqle){
sqle.printStackTrace();
}
}
}

I am unable to follow where the error is occuring

[Swastik Dey]

String url="jdbc:oracle:thin:@localhost:1521:scott";

That scott above should be the database name, not the user id.

[ragi singh]

i changed the url and username and password and still the exception stays.

Changes are:-

String url="jdbc:oracle:thin:@localhost:1521:dbname";
Connection conn=DriverManager.getConnection(url,"test","test");

[Swastik Dey]

From the sql plus window, enter the following in the user id field test/test@dbname. Does it connect?

[ragi singh]

swastik,

I am unable to connect to my database using the username and password

[Swastik Dey]

user id:test
password:test
host string:dbname

does this work?

[Swastik Dey]

A small modification, in the connection string it's not exactly the dbname, rather it's the service id.

[ragi singh]

what does a service id mean
in tnsnames.ora ?
I cant understand

[ragi singh]

but if i only give the SID how will the database name be found

[Swastik Dey]

So far as I know using a sid a particular oracle instance is identified, i.e. the address where it's located, protocol being used etc.

[Swastik Dey]

sid itself is mapped to a particular database instance.

[Swastik Dey]

If you go to administrative tools-services, you should get the names of oracle services running.

[ragi singh]

my database is MyDatabase .
After the given url used for connecting to the database ,
ie the url with SID how will a particular schema be called ?

[Swastik Dey]

Each particular sid is mapped to a particular db instance, and accordingly you have to configure listeners in tnsnames.ora. For e.g. if you have a db instance running as orcl, you may configure a sid in tnsnames.ora as orcl, and if you have another db instance running as mydatabase, you need to configure a sid for this too.

[Jan Cumps]

 

Swastik Dey wrote:Each particular sid is mapped to a particular db instance, and accordingly you have to configure listeners in tnsnames.ora. For e.g. if you have a db instance running as orcl, you may configure a sid in tnsnames.ora as orcl, and if you have another db instance running as mydatabase, you need to configure a sid for this too.

Are you talking about the server side, or the client side?

[Swastik Dey]

I haven't worked much with oracle. But as far as my knowledge goes tnsnames.ora is configured at client side. Correct me if I am wrong.

[Jan Cumps]

 

Swastik Dey wrote:I haven't worked much with oracle. But as far as my knowledge goes tnsnames.ora is configured at client side. Correct me if I am wrong.

If you use the thin client, no tnsnames configuration on client side is required.

[Swastik Dey]

Thanks
In that case what comes in place of question mark?

jdbc:oracle:thin:@localhost:1521:?

[Jan Cumps]

from http://blogs.oracle.com/theshortenspot/2009/04/advanced_oracle_jdbc_connectio.html

jdbc:oracle:thin:@[hostname]:[dbport]:[database]

where
[hostname] - Database hostname
[dbport] - Database Listener portname
[database] - Database Name

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