How to map a ResultSet with unknown amount of columns to a List and display it in a HTML table?

Question

I have created a Database Application using Netbeans, GlassFish and JavaDB. Now my controller Servlet code executes some dynamic SQL queries and get back a Result Set (or I can ahange toString). Now, how can I show the returned Result Set in a tabular format ( I have no idea about structure of result set). Can anybody help me about this ?

what problem are you having exactly? gettings the rows from the result set? generating a HTML table? show us the code you have and tell us where you're stuck. — JB Nizet
@JB Nizet, I have a code like, - createStatement(); resultset rs = st.executeQuery(sql query). Now I got stuck here. How to show this result set in a HTML table. As I have no idea about query, I have no idea about result set structure. — alessandro
@ BalusC, I have seen your reffered page. But,to apply product.setId(resultSet.getLong("id")) - this I have to know how many colums and what table the statement is returnning. I have no idea of that. — alessandro
I posted an answer. Note, to reply others in comments, please do not put a space after the @. I did not see your comment reply. — BalusC

BalusC BalusC · Accepted Answer · 2012-02-08T21:42:58

You can use Map<String, Object> to represent a "dynamic" row, which is iterable in <c:forEach>. You can use ResultSetMetaData to collect information about the columns such as the column count and the column labels.

So, this mapping should do:

List<Map<String, Object>> rows = new ArrayList<Map<String, Object>>();
ResultSetMetaData metaData = resultSet.getMetaData();
int columnCount = metaData.getColumnCount();

while (resultSet.next()) {
    Map<String, Object> columns = new LinkedHashMap<String, Object>();

    for (int i = 1; i <= columnCount; i++) {
        columns.put(metaData.getColumnLabel(i), resultSet.getObject(i));
    }

    rows.add(columns);
}

You can display it in JSP as follows:

<table>
  <thead>
    <tr>
      <c:forEach items="${rows[0]}" var="column">
        <td><c:out value="${column.key}" /></td>
      </c:forEach>
    </tr>
  </thead>
  <tbody>
    <c:forEach items="${rows}" var="columns">
      <tr>
        <c:forEach items="${columns}" var="column">
          <td><c:out value="${column.value}" /></td>
        </c:forEach>
      </tr>
    </c:forEach>
  </tbody>
</table>

How to map a ResultSet with unknown amount of columns to a List and display it in a HTML table?

2 Answers