Daten aus MySql Datenbank lesen???

[patrick_e]

Hallo,
also die Verbindung wird wunderbar hergestellt aber das Problem ist, das ich nix abrufen kann.Kann mir vielleicht jemand ne Hilfestellung geben?

public static void main(String args[]) {
        final bdesqlabfrage g = new bdesqlabfrage();
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                g.setVisible(true);
            }});
        String[] tag ={"1","2","3","4","5","6","7","8","9","10","11","12","13","14",
        "15","16","17","18","19","20","21","23","24","25","26","24","28","29","30","31"};
        String[] monat ={"1","2","3","4","5","6","7","8","9","10","11","12"};
        String[] Jahr ={"2010","2011","2012","2013","2014","2015"};
        
        String[] stunden ={"1","2","3","4","5","6","7","8","9","10","11","12","13","14","15",
        "16","17","18","19","20","21","23","24","25","26","24","28","29","30","31","32","33",
        "34","35","36","37","38","39","40","41","42","43","44","45","46","47","48","49","50",
        "51","52","53","54","55","56","57","58","59"};
        String[] minuten ={"1","2","3","4","5","6","7","8","9","10","11","12","13","14","15",
        "16","17","18","19","20","21","23","24","25","26","24","28","29","30","31","32","33",
        "34","35","36","37","38","39","40","41","42","43","44","45","46","47","48","49","50",
        "51","52","53","54","55","56","57","58","59"};
        String[] sekunden ={"1","2","3","4","5","6","7","8","9","10","11","12","13","14","15",
        "16","17","18","19","20","21","23","24","25","26","24","28","29","30","31","32","33",
        "34","35","36","37","38","39","40","41","42","43","44","45","46","47","48","49","50",
        "51","52","53","54","55","56","57","58","59"};
        
        Connection con=null;
        int stu=0,stu1=0,j=0;
        int min=0,min1=0,m=0;
        int sek=0,sek1=0,t=0;



        try{
        System.out.println("Treiber laden");

            Class.forName("com.mysql.jdbc.Driver");
            System.out.println("Treiber geladen");
            DriverManager.setLogWriter(new PrintWriter(System.out));
            System.out.println("Verbindung wird aufgebaut");
            con = (Connection) DriverManager.getConnection("jdbc:mysql://192.168.****:3306/bde", "root", "*****");
            System.out.println("Verbindung aufgebaut");

           
            stu = g.jComboBox4.getSelectedIndex();
            min=g.jComboBox5.getSelectedIndex();
            sek=g.jComboBox6.getSelectedIndex();
            
            stu1=g.jComboBox4.getSelectedIndex();
            min1=g.jComboBox4.getSelectedIndex();
            sek1=g.jComboBox4.getSelectedIndex();
            
            j=g.jComboBox1.getSelectedIndex();
            m=g.jComboBox2.getSelectedIndex();
            t=g.jComboBox3.getSelectedIndex();
            while(true){
            if (g.jCheckBox1.isSelected()) {
            //String query= "select linie,date,sum(differenz) from bde.bdetable where time between "+stunden[stu]+minuten[min]+sekunden[sek]+
            //" and "+stunden[stu1]+minuten[min1]+sekunden[sek1]+" and date ="+Jahr[j]+monat[m]+tag[t]+" group by linie;";
            String query="Select count(*) from bde.bdetable";
            java.sql.Statement st = con.createStatement();
            java.sql.ResultSet rs = st.executeQuery(query);

            while(rs.next()){
                System.out.println(rs.getString(0));
            rs.close();
            st.close();
            }
            
                
            }  con.close();
            }  
        }catch(Exception e){
        e.printStackTrace();
        }
        java.awt.EventQueue.invokeLater(new Runnable() {
            public void run() {
                new bdesqlabfrage().setVisible(true);
            }
        });
    }

Fehlercode: com.mysql.jdbc.exceptions.jdbc4.MySQLNonTransientConnectionException: No operations allowed after connection closed.
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
at com.mysql.jdbc.Util.handleNewInstance(Util.java:409)
at com.mysql.jdbc.Util.getInstance(Util.java:384)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1015)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:989)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:984)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:929)
at com.mysql.jdbc.ConnectionImpl.throwConnectionClosedException(ConnectionImpl.java:1204)
at com.mysql.jdbc.ConnectionImpl.checkClosed(ConnectionImpl.java:1191)
at com.mysql.jdbc.ConnectionImpl.createStatement(ConnectionImpl.java:2534)
at com.mysql.jdbc.ConnectionImpl.createStatement(ConnectionImpl.java:2516)
at bdemitsqlabfrage.bdesqlabfrage.main(bdesqlabfrage.java:296)

 

[Michael...]

Du rufst während des Auslesens des ResultSets close() an ihm und dem Statemtent auf.

[JAVA=64] while(rs.next()){
System.out.println(rs.getString(0));
rs.close();
st.close();
}
[/code]

 

[patrick_e]

das ist aber nicht das Problem es kommt immer noch nichts

 

[Michael...]

Naja, auf jeden Fall scheint die Verbindung zwischendurch beendet worden zu sein.
Ausserdem stimmt da was mit Deiner Klammersetzung nicht, das könnte man ja nicht mal kompilieren.

Als Tipp: Fang einfach mal klein an ohne GUI und Co.
-Verbinden, Abfragen, auf Konsole ausgeben.

und nicht alles in die public static void main(...) reinschreiben, die benutzt man nur zum Starten der Anwendung.

 

[patrick_e]

ohne GUI!!!!!

public class ohnegui {

    public static void main(String args[]) throws SQLException {
        Connection con = null;
        try{
            System.out.println("Treiber laden");
            Class.forName("com.mysql.jdbc.Driver");
            System.out.println("Treiber geladen");
            DriverManager.setLogWriter(new PrintWriter(System.out));
            System.out.println("Verbindung wird aufgebaut");
            con = (Connection) DriverManager.getConnection("jdbc:mysql://192.168.*****:3306/bde", "root", "*****");
            System.out.println("Verbindung aufgebaut");
        }
        catch(Exception e){
            e.printStackTrace();
        }
        String query= "select linie,date,sum(differenz) from bde.bdetable where time between 070000 and 143000 and date =100331 group by linie;";

        java.sql.Statement st = con.createStatement();
        java.sql.ResultSet rs = st.executeQuery(query);

            System.out.println(rs.getString(0)+"-->"+rs.getString(1));
        
     rs.close();
     st.close();
     con.close();
    }

}

Fahlercode:Verbindung aufgebaut
SQLState(S1000) vendor code(0)
Exception in thread "main" java.sql.SQLException: Before start of result set
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:1075)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:989)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:984)
at com.mysql.jdbc.SQLError.createSQLException(SQLError.java:929)
at com.mysql.jdbc.ResultSetImpl.checkRowPos(ResultSetImpl.java:842)
at com.mysql.jdbc.ResultSetImpl.getStringInternal(ResultSetImpl.java:5657)
at com.mysql.jdbc.ResultSetImpl.getString(ResultSetImpl.java:5577)
at ohnegui.main(ohnegui.java:35)
Java Result: 1

 

[Michael...]

Der Zeiger des ResultSets ist noch nicht positioniert, ausserdem könntest Du so auf einen Fehler laufen, wenn der ResultSet kein Ergebnis liefert --> while(rs.next()) vor Zeile 22

 

[patrick_e]

Danke hat funktioniert!!!!