Question

I have 6 columns in a table. I have a select query which selects some records from the table. While iterating over the result set, im using the following logic to extract the values in the columns:

Statement select = conn.createStatement();
        ResultSet result = select.executeQuery
        ("SELECT * FROM D724933.ECOCHECKS WHERE ECO = '"+localeco+"' AND CHK_TOOL = '"+checknames[i]+"'");
         while(result.next()) { // process results one row at a time
           String eco = result.getString(1);
           mapp2.put("ECO", eco);
           String chktool = result.getString(2);
           mapp2.put("CHECK_TOOL", chktool);
           String lastchktime = result.getString(3);
           mapp2.put("LAST_CHECK_TIME", lastchktime);
           String status = result.getString(4);
           mapp2.put("STATUS", status);
           String statcmts = result.getString(5);
           mapp2.put("STATUS_COMMENTS", statcmts);
           String details = result.getString(6);
           mapp2.put("DETAILS_FILE", details);
         }            

I have 2 questions here:
1. Is there any better approach rather than using result.getString()???
2. Lets say, another column gets added to the table at a later point. Is there any way my code handles this new addition without making change to the code at that point of time

Answer 1

You can use ResultSetMetaData to determine the number and names of the columns in your ResultSet and deal with it this way. Note however that changing the number of columns in the database – affecting your code – and having the code still work may not always be a good idea.

Additionally, note that you’re overwriting the values in your map on each iteration of the loop. You probably want to add those maps to some sort of List?

Finally, you need to make sure that your getString methods will not return null anywhere, otherwise putting it into a map will throw an exception.

Statement select = conn.createStatement();
ResultSet result = select.executeQuery("SELECT * FROM D724933.ECOCHECKS WHERE ECO = '"+localeco+"' AND CHK_TOOL = '"+checknames[i]+"'");
ResultSetMetaData rsmd = result.getMetaData();

int numberOfColumns = rsmd.getColumnCount();    
List data = new ArrayList<Map>();
Map mapp2;

while(result.next()) { // process results one row at a time
    mapp2 = new HashMap<String, String>();
    for(int i=1; i<=numberOfColumns; i++) {
        mapp2.put(rsmd.getColumnName(i), rs.getString(i));
    }
    data.add(mapp2);
}