Question

I have a query string that is dynamic. The items I am searching for in the database are based upon what the user selects in a checkbox on an html form. The user types selects a city name from a drop down list. Then the user can select from 3 different attributes to the city: CountryCode(int), District(String), and Population(int).

I have no problem creating the query. For example if the user selects Tulsa and selects District and Population the queryString SELECT District, Population FROM City WHERE name ='Tulsa' is created no problem. For another example if the user simply selected country code of Tulsa the query string created would be SELECT CountryCode FROM City WHERE name ='Tulsa'.

The problem is parsing the data and displaying it neatly to the screen. I am no database programmer so I am having a tough time. Here is a tidbit of my code so you can see what I’m doing.

The only thing I can do correctly is if the user selects District and Population. Any other selection doesn’t work. I am basically hard coding District and Population. I am not sure how to parse it dynamically. Here is the code. Query string is SELECT District, Population FROM City WHERE name ='Tulsa'. Its the only one I can get to work.

public String getData( String c)
    {

        String query = c;
        ResultSet rs = null;
                StringBuffer back = new StringBuffer();

        try
        {
            rs = st.executeQuery(c);
            ResultSetMetaData rsmd = rs.getMetaData();

            int numColumns = rsmd.getColumnCount();
            back.append( "number of columns is " + numColumns);
                        back.append( "</br>");

            back.append( "<table border=\"10\" >\n" );
                        while(rs.next())
                        {
                            if(rsmd.getColumnTypeName(1).equals("CHAR"))
                                back.append("<tr><td>" + rsmd.getColumnName(1) + "</td>" + "<td>" + rs.getString(1) + "</trd</tr>");

                            if(rsmd.getColumnTypeName(2).equals("INT"))
                                back.append("<tr><td>" + rsmd.getColumnName(2) + "</td>" + "<td>" + Integer.toString(rs.getInt(2)) + "</td></tr>");

            }
            back.append( "</table>" );
        }
        catch( SQLException e )
        {
            back.append( "<h6>something bad is happening</h6>");
            e.printStackTrace();
            return null;
        }
        return new String( back );
    }

I hope you guys understand what I’m asking. Thanks alot for the help!

Answer 1

If all you want to do is output the data, you can just get everything as a String using ResultSet.getString(index) since you know the number of columns from your metadata.

while(rs.next())
{
    for (int i = 1; i <= numColumns; i++)
    {
        back.append("<tr><td>" + rsmd.getColumnName(i) +
                    "</td>" + "<td>" + rs.getString(i) + "</trd</tr>");
    }
}