Read one record at a time

Hi !
One of our Java folks here need at function where he reads one record at at time in id order;
create table url_recs (id number, url varchar2(4000));
insert into url_recs values(1,'www.fona.dk');
insert into url_recs values(2,'www.dr.dk');
insert into url-recs values(17,'www.ihk.dk');
select read_rec() from dual; - get id 1
select read_rec() from dual; - get id 2
select read_rec() from dual; - get id 17
select read_rec() from dual; - get id 1 - "no more rows - start all over again)
select read_rec(45) from dual; - get NULL (no rows with that id)
select read_rec(1) from dual; - get id 1
The purpose id for some "round robin" trying to get to some internal URL's.
Can you give me a hint for creating the function(s)
best regards
Mette

Will successive calls come on the same Oracle session? Or across different Oracle sessions?
If you're going to call the function multiple times within the same Oracle session, you could store the last value returned in a package variable and select the record whose ID is greater than that value every time the function is called. That's unlikely to do exactly what the Java developer is hoping, though, because the Java calls are likely to bounce between multiple Oracle sessions due to connection pooling. And it'll likely require that the Java developer (or app server admin) adds some code when they get a connection from the pool where they reset the package state. Or it'll require that someone develop a method to keep the Java and Oracle session state in sync.
Justin

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Challenge involving creating a file on GUI & seeing one record at a time...

Hi,
If anyone can help me with this project I'd be most appreciative. I'll try and explain the problem the best I can. I'm adding students to a database at a university they're either a Graduate or an Undergraduate. I'm taking in first, lastname's, ssn, & ACT/SAT/GMAT test results. I have a GUI called StudentRecord that has all the JTextFields, JButton's, etc. I'm also writing it to a .txt file called StudentDA. For this I used a BufferedFile reader.
What I really need is on my StudentRecord when I click the display button I want it to show one record at a time in another JFrame. This other JFrame I named it display. I'm trying to create an instance of JFrame inside of the actionPerformed for StudentRecord but when I click display nothing happens.
I adding the students with a vector that I'm calling v. I want the Display to read from the .txt file and display one at a time hence next, and previous. I'm going to post the tidbit of relevant code. If anyone can help me you'd be my hero for the day for all time I've tried to get this to work.
Here's the StudentRecord (GUI) display part:
      public void actionPerformed( ActionEvent event )
     try {
          Display d = new Display(StudentDA.v);
         }//end try
        //catch right here no problems with this..Here's the DataAccess part:
public class StudentDA{
static Vector v = new Vector();;
static String pathName = "a:/Final Project/test1.txt";
static File studentFile = new File(pathName);
static String status;
public StudentDA() {}
public static void initialize() {
    if (studentFile.exists() && studentFile.length() !=0) {
     try{
      BufferedReader in = new BufferedReader(new
      FileReader(studentFile) );
      do{
         status = in.readLine();
          if(status.equals ("uGrad")) {
            uGrad u = new uGrad();
            u.setFName(in.readLine() );
            u.setLName(in.readLine() );
            u.setssNum(Integer.parseInt(in.readLine()) );
            u.setACT(Integer.parseInt(in.readLine() ));
            v.add(u);
            System.out.println(u + "inside ugrad");
          }//end if uGrad
          else{
            if(status.equals("Grad")) {
            //same process as uGrad
            v.add(g);
          }//end else Grad
      }while (status != null);
    }//end try statement
    catch (Exception e) {
      }//end catch
    }//end if there's something there
}//end method initialize
//creating the terminate method
public static void terminate() {
    try{
      PrintStream out = new PrintStream ( new
      FileOutputStream (studentFile) );
      for (int i = 0; i < v.size(); i++) {
        Student s = (Student) v.elementAt(i);
        String p = s.printRecord();
        StringTokenizer rt = new StringTokenizer(p, "\t");
        while (rt.hasMoreTokens() ) {
          out.println(rt.nextToken() );
          }//end while
      }//end for loop
    }//end try loop
    catch (Exception e){
    }//end catch
}//end terminate
public static void add(Student s){// throws DuplicateException{
          boolean duplicate = false;
          for(int i = 0; i < v.size(); i++){
               if(s.getssNum() == ((Student)(v.elementAt(i))).getssNum()){
                    duplicate = true;
                    break;
               if(duplicate){
                    throw new DuplicateException("Student Already Exists");
               else{
                    v.add(s);
}//end add method
}//end classHere's the display class:
public class Display extends JFrame {
     private JButton Next, Previous;
     private JTextField statusField, firstField, lastField, socialField, advPlacementField, actField;
     private JLabel statusLabel, firstLabel, lastLabel, socialLabel, advPlacementLabel, actLabel;
     private JPanel fieldPanel, buttonsPanel;
     private JTextArea displayArea;
     static int count = 0;
     static String status;
     public Display(){}
public Display(Vector v){
     //setting up the GUI components for the display class here
     //JTextAreas & JLabels
     buttonsPanel = new JPanel();
     buttonsPanel.setLayout(new GridLayout(1,2));
    Next = new JButton("Next");
    buttonsPanel.add(Next);
    Next.addActionListener(
    new ActionListener() {
      public void actionPerformed( ActionEvent event )
          //try to catch display errors
       try {
                    count++;
                 displayData(count);
                 //displayData();
      }//end try
          catch {
         }//end catch
      } // end actionPerformed
    } // end anonymous inner class
    ); // end call to addActionListener
    buttonsPanel.add(Next);
    Previous = new JButton("Previous");
    buttonsPanel.add(Previous);
    Previous.addActionListener(
    new ActionListener() {
      public void actionPerformed( ActionEvent event )
          //try to catch display errors
          try {
               count--;
               displayData(count);
               //displayData();
         }//end try
          catch {
         }//end catch
      } // end actionPerformed
    } // end anonymous inner class
    ); // end call to addActionListener
}//end display() constructor
public void displayData(int count) {
     StudentDA.initialize();
       if (status.equals ("uGrad")) {
       //these are all part of the StudentRecord GUI not Display GUI
            fieldPanel.setVisible(true);
            buttonsPanel.setVisible(true);
            actLabel.setVisible(true);
            actField.setVisible(true);
            advPlacementLabel.setVisible(false);
            advPlacementLabel.setVisible(false);
       }//end if
       else {
            if(status.equals ("Grad")) {
             fieldPanel.setVisible(true);
             buttonsPanel.setVisible(true);
             actLabel.setVisible(false);
             actField.setVisible(false);
             advPlacementLabel.setVisible(true);
             advPlacementLabel.setVisible(true);
              }//end if
       }//end else
}//end method displayData()
public static void main ( String args[] )
    Display application = new Display();
    application.addWindowListener(
          new WindowAdapter(){
               public void windowClosing( WindowEvent e)
                    System.exit(0);
    application.setSize( 300, 200);
    application.setVisible( true );
};//end main
}//end class Display{}I know this is long but if anyone can help I'd greatly appreciate it. Please ask me if you need me to clarify something, I tried to not make it way too long. --rockbottom01


I'm not really too sure what it is that you are after, but here is some code, that loads up an array with each line of a .txt file, then displays them. I hope you can make use of a least some of it.
just ask if you don't understand any of the code.
String array[];
int i;
public Test() {
          readFile("file.txt");
          i = 0;
          nextEntry();
     public void nextEntry() {
          Display display = new Display();
          display.show();
     class Display extends JFrame implements ActionListener {
          JLabel label1;
          JButton button;
          public Display() {
               label1 = new JLabel(array);
               button = new JButton("OK");
               getContentPane().setLayout(new FlowLayout());
               getContentPane().add(label1);
               getContentPane().add(button);
               button.addActionListener(this);
          public void actionPerformed(ActionEvent e) {
               setVisible(false);
               i++;
               if(i < array.length) {
                    nextEntry();
     public void readFile(String fileName) {
          String s, s2 = "";
          int lineCount = 0;
          BufferedReader in;
          try {
               in = new BufferedReader(new FileReader(fileName));
               while((s = in.readLine()) != null) {
                    lineCount++;
               array = new String[lineCount];
               in.close();
               in = new BufferedReader(new FileReader(fileName));
               int j = 0;
               while((s = in.readLine()) != null) {
                    array[j] = s;
                    j++;
          catch(IOException e) {
               System.out.println("Error");

Return only one record at a time

I am new to crystal reports so any help would be appreciated. I have a .net app that is a order processing system. When the user is in a record, they want to be able to click on a button an open a crystal report showing only that orders details. I created a crystal report that has the following fields:
Order ID, Product ID, Unit Price, Sell Price, Hours.
The Order ID is the primary key in the database. The report runs fine when clicking the report button in the app, but returns the details for every order in the database. We just need the details of the order that the user is processing. How do I setup the report to only show that order's details? I am using VB 2005 and Crystal v9.
Edited by: sking on Mar 6, 2009 1:12 AM

Brian,
Thank you for all your help. I have been able to setup the report to return only one record at a time. In my app, when I click the report button the PDF opens perfectly with only one record. However, when I go to another record and open the PDF it returns the information from the record id that was set as the default parameter value (crReportDocument.SetParameterValue("Orders", 67). How do I get it to return the report for a different record? Here is the code I'm using. I think I'm really close with your suggestions but I'm just missing one step.
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      Else
          crReportDocument.Load(Me.Page.MapPath(fileName))
      End If
      Catch ex As Exception
          Dim errMsg As String = ex.Message.Replace(Chr(13).ToString(), "").Replace(Chr(10).ToString(), "")
          errMsg += " Please make sure the dlls for Crystal Report are compatible with the Crystal Report file."
          BaseClasses.Utils.MiscUtils.RegisterJScriptAlert(Me, "BUTTON_CLICK_MESSAGE", errMsg)
      End Try
      Try
Dim paramValue As CrystalDecisions.Shared.ParameterDiscreteValue = New CrystalDecisions.Shared.ParameterDiscreteValue()
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           crReportDocument.SetParameterValue("Orders", 67)
DisplayReportAsPDF_CrystalReportButton(crReportDocument)
      Catch ex As Exception
          Dim errMsg As String = ex.Message.Replace(Chr(13).ToString(), "").Replace(Chr(10).ToString(), "")
          errMsg += " If this is a deployment machine, make sure network service has permissions to read or write to the windows\temp folder."
          BaseClasses.Utils.MiscUtils.RegisterJScriptAlert(Me, "BUTTON_CLICK_MESSAGE", errMsg)
      End Try

Master_detail for more than one record at a time

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How can i display master_detail records for more than one records at a time, for example, i have two tables A and B , A has username and role and B has username and profile. here i wanted to display 10 users at a time on my 6i form with username, role and profile.
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Thanks for your help.Bcj

Thanks Roberts, that was realy informative due to some doubts i would like to confirm my requirements , i have two blocks A and B and each master record has only one detail record. but i wanted to display at least 10 master_detail relationships(records) on the form at a time, i would like to know is it possible to do without creating any table or view for example,
data in table A,
username role
AAA R1
BBB R2
CCC R3
data in table B,
username profile
AAA P1
BBB P2
CCC P3
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AAA R1 P1
BBB R2 P2
CCC R3 P3
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Certified LabVIEW Architect, Certified TestStand Developer
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Reading one character at a time

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I have tried to use
ir=new InputStreamReader(System.in)
ir.read().
But this method blocks until it gets a return key pressed before going forward
Any other solution?

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int ch;
char r = '\0';
boolean done = false;
while (!done) {
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ch = System.in.read();
r = (char) ch;
if (r == '\r') {
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System.in.skip(1);
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public static char readChar() {
int ch;
char r = '\0';
boolean done = false;
while (!done) {
try {
ch = System.in.read();
r = (char) ch;
if (r == '\r') {
System.out.println("Not a character. Please try again!");
System.in.skip(1);
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System.in.skip(2);
done = true;
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Note 1575981
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null

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int ch;
char r = '\0';
boolean done = false;
while (!done) {
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Is any body able to help me? I need to display one record at a time from a Select statement.
Could I copy the results of the Select query from a table into an array for later display or is there a better alternative.
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http://asktom.oracle.com/pls/ask/f?p=4950:8:::::F4950_P8_DISPLAYID:127412348064
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Read one record at a time

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