How to Query a Record from the Database 2

[tonioJ]

Hello I am new to JAVA using JDBC. But I already have and understanding how it works. I just want to ask a question what is wrong with my source code because I keep on getting an error saying Driver is not found: the source code is below:

import java.sql.*;

public Connection cnn = null;

private void btnConnectSQLActionPerformed(java.awt.event.ActionEvent evt) {
// TODO add your handling code here:

ConnectToSQL();
GetRecords();

}

private void GetRecords(){

try{
String mySQLStatement = "Select * from FRIENDSLIST";
Statement stmt = cnn.createStatement();
ResultSet rs=stmt.executeQuery(mySQLStatement);


//PreparedStatement stmt = cnn.prepareStatement(mySQLStatement);
//ResultSet rs.stmt.executeQuery();


if (rs.getFetchSize() != 0) {
txtLastName.setText(rs.getString("LAST_NAME"));
};




} catch(NullPointerException e){
System.out.println("NullPointerException");
}
catch(Exception e){
System.out.println("Query Failed !");
}
}

private void ConnectToSQL(){
try {
// jdbc:jtds:sqlserver://<hostname>[:<port][/<dbname>][;<property>=<value>[;...]]


String driverName = "net.sourceforge.jtds.jdbc.Driver"; // NetDirect JDBC driver
String serverName = "197.121.7.15";
String portNumber = "1433";
String mydatabase = serverName + ":" + portNumber + "/JavaSample";
String url = "jdbc:jtds:sqlserver://" + mydatabase; // a JDBC url
String username = "sa";
String password = "admin";

// Load the JDBC driver
Class.forName(driverName);

// Create a connection to the database
cnn = DriverManager.getConnection(url, username, password);
}catch (ClassNotFoundException e) {
// Could not find the database driver
System.out.println("Could not find DB Driver");
} catch (SQLException e) {
// Could not connect to the database
System.out.println("Could not connect to DB");
}


}

 

[Diancecht]

Maybe some more details about the erros should be useful, but at first sight it seems that the driver class files is not in the classpath.

Cheers.

Dian.

 

[tonioJ]

yeah you're right Dian,

how will I do it??? I mean how will I put the driver class file in the classpath?? And where can I find this classpath??

 

[sedj]

if you are in something like tomcat, then add the jtds driver .jar file to TOMCAT_HOME/common/lib.

If you are running the class from the command line or a console, then stype this before your run the code :

(on dos/windows)
set CLASSPATH=%CLASSPATH%;C:\where\my\jar\file\is\jar_file_name.jar

(on linux/unix)
export CLASSPATH=$CLASSPATH;/where/my/jar/file/is/jar_file_name.jar

--------------------------------------------------
Free Database Connection Pooling Software

http://www.primrose.org.uk

 

[tonioJ]

guys, thanks for all your help...

i can already connect to the database but still it's returning an error... i couldn't get to query the records inorder for me to diplay them on the text fields.

i have 3 records in my table. the fetchsize of the resultset is 1 and it returns an error

java.sql.SQLException: Cursor may only be accessed in a forward direction.

 

[sedj]

>>> java.sql.SQLException: Cursor may only be accessed in a forward direction.

Your code is a bit incorrect - it should be more like :

ResultSet rs=stmt.executeQuery(mySQLStatement);
while (rs.next()) {
    txtLastName.setText(rs.getString("LAST_NAME"));
}

--------------------------------------------------
Free Database Connection Pooling Software

http://www.primrose.org.uk

 

[tonioJ]

sedj,

thanks for your help. i was able to figure it out.

with this code:
ResultSet rs= null;
rs = stmt.executeQuery(mySQLStatement);
rs.beforeFirst();
rs.next();

at least this will be my stepping stone to database application development using java....

 

[haslo]

Looking good
There's no need to initialize the rs with null first though, try this:

ResultSet rs = stmt.executeQuery(mySQLStatement);
rs.beforeFirst();
rs.next();

haslo@haslo.ch - www.haslo.ch​

 

[Diancecht]

Anyway, I think initializing variables is a good practise. That can avoid scope problems, "spurious" data in loops and so on.

Cheers.

Dian