netbeans database problem

[bikkerss]

i'm a novice in programming and i have the following problem
i'm trying to fill a combobox with strings collected from the resultset from a query.
with numbers i can get it to work but not white strings can sombody show my an example ?

i get the error table/view *** not exist

[Fubarable]

Why not show us your code (with code tags) and the actual error message?

[bikkerss]

here it is

db class

 public class DATABANK
{
public Connection conn = null;
public Statement stmt = null;
public ResultSet rs = null;

public DATABANK(String sql)
{
try {
String dbURL = "jdbc:derby://localhost:1527/INFOREGISTRATIE";
Class.forName("org.apache.derby.jdbc.ClientDriver" );
conn =DriverManager.getConnection(dbURL);

stmt = conn.createStatement(ResultSet.TYPE_SCROLL_INSENSI TIVE, ResultSet.CONCUR_UPDATABLE);
rs=stmt.executeQuery(sql);

//rs.close();
}
catch (Exception ex)
{
JOptionPane.showMessageDialog(null,ex.getMessage() );

}

}
}

event

 private void jComboBoxmedewerkerMouseClicked(java.awt.event.Mou seEvent evt) { 
databankmedewerkers= new DATABANK("select * from MEDEWERKERS where MEDEWERKERNAAM= " + jComboBoxmedewerker.getSelectedItem());
try {
databankmedewerkers.rs.first();

medewerker.setText(databankmedewerkers.rs.getString("medewerkernaam"));
databankmedewerkers.rs.close();
} catch (SQLException ex) {

}
}

[bikkerss]

Nobody that sees the problem ?

[Fubarable]

Nobody that sees the problem ?

You may wish to post the error messages as was requested above, and use code tags (as was requested above).

[bikkerss]

Error code:

Syntax error: Encountered "null" at line 1 column 49

Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
at eindwerkinfovragen.INGAVEFORM.jComboBoxmedewerkerM ouseClicked(INGAVEFORM.java:795)
at eindwerkinfovragen.INGAVEFORM.access$100(INGAVEFOR M.java:25)
at eindwerkinfovragen.INGAVEFORM$2.mouseClicked(INGAV EFORM.java:271)
at java.awt.AWTEventMulticaster.mouseClicked(AWTEvent Multicaster.java:253)
at java.awt.Component.processMouseEvent(Component.jav a:6266)
at javax.swing.JComponent.processMouseEvent(JComponen t.java:3267)
at java.awt.Component.processEvent(Component.java:602 8)
at java.awt.Container.processEvent(Container.java:204 1)
at java.awt.Component.dispatchEventImpl(Component.jav a:4630)
at java.awt.Container.dispatchEventImpl(Container.jav a:2099)
at java.awt.Component.dispatchEvent(Component.java:44 60)
at java.awt.LightweightDispatcher.retargetMouseEvent( Container.java:4574)
at java.awt.LightweightDispatcher.processMouseEvent(C ontainer.java:4247)
at java.awt.LightweightDispatcher.dispatchEvent(Conta iner.java:4168)
at java.awt.Container.dispatchEventImpl(Container.jav a:2085)
at java.awt.Window.dispatchEventImpl(Window.java:2475 )
at java.awt.Component.dispatchEvent(Component.java:44 60)
at java.awt.EventQueue.dispatchEvent(EventQueue.java: 599)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(E ventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispa tchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThre ad.java:122)


it's weird beceause i don't have 49 colums

[r035198x]

What is line 795 of INGAVEFORM.java?

[bikkerss]

databankmedewerkers.rs.first();

[Fubarable]

So either databankmedewerkers or databankmedewerkers.rs is null. You will need to find out why.

[bikkerss]

whitch would indicate the query is empty or do i miss understand ?
i have filled the database

[Tolls]

A resultset will not come back null* from a query. It will simply be empty (this is not the same as null).

However this - "Syntax error: Encountered "null" at line 1 column 49" - is a SQL error, implying you have a problem in your SQL statement. Since you then continue on in your code it seems you ignore this problem and assume your query has worked.

I'm guessing a bit, but I suspect it's down to you concatentiaing your query together rather than using a PreparedStatement.


* - Except for one db that eludes me at the moment, but it's not likely to be the one you're using.