Why I am not able to entry data into sqlite database using JDBC java?

Question

I am trying to make a ledger (to keep records of sales). I am using sqlite and netbeans. The problem is that my INSERT query is not adding data to the database and the console is also not showing any error . The program consists of 2 files ledger.java and ledgerGUI.java . ledger.java contains the function definitions to carry out sql queries. These functions are called in ledgerGUI.java to add data from JTextField .

Part of the code of ledger.java

  package ledger;
  import java.sql.*;

  public class Ledger  {
  public Connection c = null;
  public Statement stmt = null;

  private String name_db = "";
  private String tm_db = "";
  private String item_db = "";
  private int quantity_db = 0;
  private int price_db = 0;   

// Connecting to the database.
public void connectDb(){        
    try{
        Class.forName("org.sqlite.JDBC");
        c = DriverManager.getConnection("jdbc:sqlite:Ledger.db");

    } 
    catch ( ClassNotFoundException | SQLException e ){        
    }    
}

// Query
public void insertToDb(String name_entry, String tmark_entry, String item_entry, int quantity_entry, int price_entry){
    name_db = name_entry;
    tm_db = tmark_entry;
    item_db = item_entry;
    quantity_db = quantity_entry;
    price_db = price_entry;

    try{
        connectDb();
        stmt = c.createStatement();
        String query = "INSERT INTO ledger_table (Name, Trade Mark, Item, Quantity, Price) VALUES (name_db, tm_db, item_db, quantity_db, price_db)";
        stmt.executeUpdate(query);            
        stmt.close();
        c.commit();
        c.close();           

    }
    catch(Exception e){            
    }             
}

Part of the code of ledgerGui.java

 private void submitActionPerformed(java.awt.event.ActionEvent evt) {                                       
   Ledger lg = new Ledger();
   String name = tf_name.getText();
   String tmark = tf_tmark.getText();
   String item = tf_item.getText();
   int quantity = Integer.parseInt(tf_quantity.getText());
   int price = Integer.parseInt(tf_price.getText());
   try{
       lg.insertToDb(name, tmark.toUpperCase(), item, quantity, price);
   }
         catch(Exception e){      
    }
   tf_item.setText("");
   tf_quantity.setText("");
   tf_price.setText("");
}            

Answer 1

You can use PreparedStatement , something like this:

// Query
public void insertToDb(String name_entry, String tmark_entry, String item_entry, int quantity_entry, int price_entry){
    name_db = name_entry;
    tm_db = tmark_entry;
    item_db = item_entry;
    quantity_db = quantity_entry;
    price_db = price_entry;
try{
    connectDb();
    String query =
        "INSERT INTO ledger_table (Name, Trade Mark, Item, Quantity, Price) VALUES (?, ?, ?, ?, ?)";        
    PreparedStatement statement = c.prepareStatement(query);
    statement.setString(1, name_db);
    statement.setString(2, tm_db);
    statement.setString(3, item_db);
    statement.setInt(4, quantity_db);
    statement.setInt(5, price_db);
    statement.executeUpdate();            
    c.commit();
    c.close();           

}
catch(Exception e){            
}             
}

Are you sure that Trade Mark has a spaces separator on the table of database...

INSERT INTO ledger_table (Name, Trade Mark, Item, Quantity, Price)...