How to connect two different excel files as databases on the same server in java?

Question

I have two excel databases connected using two different connection variables con1 and con2.I want to retrieve data from my second database by matching the columns in both the databases.How can I do this in java?I have tried this much. I am getting NullPointerException when I run this code.

try
{
    sql10 = "select [Data$].Species,[Plot$].District,[Plot$].State from [Plot$],[Data$] where [Data$].Plot_ID = ? ";
    pst10=con.prepareStatement(sql10);
    pst10.setString(1, tmp1);
    rs14=pst10.executeQuery();

    while(rs14.next())
    {
        String st=rs14.getString("State");
        String dis=rs14.getString("District");
        String sp=rs14.getString("Species");
        System.out.println(sp);
        sql11="select * from [database$] where State = st  and District = dis and Species = sp";
        pst11=con1.prepareStatement(sql11); 
        pst11.setString(1, tmp1);
        rs15=pst11.executeQuery();

        while(rs15.next())
        {
            System.out.println(rs15.getString("Local_equation"));
        }
    }

Stack trace is:

java.lang.NullPointerException
    at sun.jdbc.odbc.JdbcOdbcPreparedStatement.clearParameter(JdbcOdbcPreparedStatement.java:1022)
    at sun.jdbc.odbc.JdbcOdbcPreparedStatement.setChar(JdbcOdbcPreparedStatement.java:3056)
    at sun.jdbc.odbc.JdbcOdbcPreparedStatement.setString(JdbcOdbcPreparedStatement.java:765)
    at biomasscal.GLA14.buttonCALCULATEActionPerformed(GLA14.java:599)
    at biomasscal.GLA14.access$400(GLA14.java:60)
    at biomasscal.GLA14$5.actionPerformed(GLA14.java:279)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2018)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2341)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(BasicButtonListener.java:252)
    at java.awt.Component.processMouseEvent(Component.java:6504)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3321)
    at java.awt.Component.processEvent(Component.java:6269)
    at java.awt.Container.processEvent(Container.java:2229)
    at java.awt.Component.dispatchEventImpl(Component.java:4860)
    at java.awt.Container.dispatchEventImpl(Container.java:2287)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4832)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4492)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4422)
    at java.awt.Container.dispatchEventImpl(Container.java:2273)
    at java.awt.Window.dispatchEventImpl(Window.java:2713)
    at java.awt.Component.dispatchEvent(Component.java:4686)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:707)
    at java.awt.EventQueue.access$000(EventQueue.java:101)
    at java.awt.EventQueue$3.run(EventQueue.java:666)
    at java.awt.EventQueue$3.run(EventQueue.java:664)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:87)
    at java.awt.EventQueue$4.run(EventQueue.java:680)
    at java.awt.EventQueue$4.run(EventQueue.java:678)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:677)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:211)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:128)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:117)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:113)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:90)

@LiamWilson94-Thanks for your help.Thanku so much. It worked. — Aparna Pathak
– Aparna Pathak, Commented Apr 2, 2015 at 16:52

LiamWilson94 · Accepted Answer · 2015-04-02 15:34:10Z

1

When you query your second excel database you need to pass the variables from the first query in as parameters (as you did previously):

 sql11="select * from [database$] where State = ? and District = ? and Species = ?";
     pst11=con1.prepareStatement(sql11); 
     pst11.setString(1, st);
     pst11.setString(2, dis);
     pst11.setString(3, sp);
     rs15=pst11.executeQuery();

However, with out seeing the full stack trace, I cannot be sure.

answered Apr 2, 2015 at 15:34

LiamWilson94

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Aparna Pathak Over a year ago

@LiamWilson94-This query on two result sets is displaying values that match with each other. Now if I want to display the values that do not match with each other what query should I use?Like if I want to display the value of species then what should I do?can you please help me out?

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