Viewing multiple rows in a database.

Question

Hey,
I've been stuck on a problem for a while now. I know that JDBC 1.0 does not allow scrollable resultsets or provide a rowcount method. I know because of this two resultsets are needed,one to get the number of rows and the other to get the values from the rows. Both return the same result set. However when doing this I keep catching an SQL Exception and I dont know why.
The code is in a method in a session EJB but should it not work the same? I shall copy my code in and maybe someone could point out my mistake!
public String[] viewAuctions(TestAuctionVO auctionVO)
// The url for the database
String url = "jdbc:odbc:ProjectDS";
String dbDriver = "sun.jdbc.odbc.JdbcOdbcDriver";
Connection con = null;
Statement stmt = null;
Statement stmt2 = null;
ResultSet rs = null;
ResultSet rs2 = null;
Integer ID = auctionVO.getID();
Integer sellerID = auctionVO.getSellerID();
// Load the driver...
try
               con = DriverManager.getConnection(url,"","");   //  Create a connection
          stmt = con.createStatement();
          stmt2 = con.createStatement();
          //  Build up the SQL statement
                String mySQLstmt = ("SELECT * FROM AUCTION WHERE proposedEndDate > GetDate()");
                System.out.println("Statement is "+mySQLstmt);
          rs =  stmt.executeQuery(mySQLstmt);
                rs2 = stmt2.executeQuery(mySQLstmt);
                System.out.println("Result Set 1 is "+rs);
                System.out.println("Result Set 2 is "+rs2);
          int numRows = 0;
          // While there is another row in the resultset...
          while(rs2.next())
                   // ...another element will be needed in the String array
               numRows++;
                       System.out.println("Number Rows: "+numRows);
          // Only perform this section if there is at least one row in theResultSet
          if (numRows > 0)
               //  Set up an array of strings to hold the rows
               String[] auctions = new String[numRows];
                        System.out.println("Number Rows: "+auctions);
               //  Counter to access the array elements
               int i = 0;
                        System.out.println("i : "+i);
               //  While there is another row
               while(rs.next())
                                 System.out.println("There is another record...");
                                   ID = new Integer(rs.getInt(1));
                                ID.toString();
                    System.out.println("\nID = " + ID);
                                 sellerID = new Integer(rs.getInt(2));
                                 sellerID.toString();
                    System.out.println("Seller ID = "+sellerID);
                                 //...and so on
                         //  Build up the string to store in the array
                String userdetails = ID + "," + sellerID + "," ...............
               //  Put the string in the string array
               auctions[i] = userdetails;
               //  Increment the counter so this element is not overwritten
               i++;
          //  Let User know how many rows were returned
          System.out.println("\n Array has : "+auctions.length+" Elements\n");
          //  For each element in the array
          for(int j=0 ; j< numRows; j++)
               //  If the element is not empty
               if(!(auctions[j].equals(null)))
                    int ElemNum = j+1;
          System.out.println(" ViewAuctionEJB viewAuctions method exited");
          System.out.println(" Successfull");
                 System.out.println("Auction Array: "+auctions);
                 return auctions;
     else  //  If there were no elements in the result set
          System.out.println(" ViewAuctionEJB viewAuctions method exited");
          System.out.println(" Unsuccessfull: No elements in ResultSet");
     stmt.close();
        stmt2.close();
     con.close();
catch (SQLException sQLE)    //  There may have been an error in the execution of
{                            //  the SQL code
     System.out.println(" ViewAuctionEJB viewAuctions  method exited");
     System.out.println(" Unsuccessfull: Error in SQL code");
        String[] fail = new String[1] ;
        return fail;
String[] success = new String[1] ;
return success;
}Any help is appreciated!
Thanks

Answer 1

Not all databases and JDBC drivers support multiple open cursors per connection.
Instead of trying to count rows, define an Auction object. Read Auction objects from the database, and put them in a vector. Return the vector of Auctions (or convert it to an array of Auctions.) If you need a String[] representation, write a function that converts Auction[] to String[] -- nicer separation of duties at least.
That'll be more reliable, too, as the number of rows can't change between the two cursor loops.