Question

I have this Java code which is used for JSF pagination:

public List<ActiveSessionObj> list(int firstRow, int rowCount, String sortField, boolean sortAscending) throws Exception {

        String SQL_LIST_BY_ORDER_AND_LIMIT = "SELECT * FROM ACTIVESESSIONSLOG ORDER BY ? ? LIMIT ?, ?";



        if (ds == null) {
            throw new SQLException();
        }

        String sortDirection = sortAscending ? "ASC" : "DESC";
        String sql = String.format(SQL_LIST_BY_ORDER_AND_LIMIT, sortField, sortDirection);
        Connection conn = ds.getConnection();
        PreparedStatement preparedStatement = null;
        ResultSet resultSet = null;
        List<ActiveSessionObj> dataList = new ArrayList<ActiveSessionObj>();

        try {
            conn.setAutoCommit(false);
            boolean committed = false;
            preparedStatement = conn.prepareStatement(sql);
            preparedStatement.setString(1, sortField);
            preparedStatement.setString(2, sortDirection);
            preparedStatement.setInt(3, firstRow);
            preparedStatement.setInt(4, rowCount);

            resultSet = preparedStatement.executeQuery();
            /* take the result from the SQL query and insert it into Array List collection */
            dataList = ActiveSessionsArrayList(resultSet);

        } catch (SQLException e) {
            throw new Exception(e);
        } finally {
            conn.close();
        }

        return dataList;
    }

I use this SQL statement to generate ArrayList:

SELECT * FROM ACTIVESESSIONSLOG ORDER BY ? ? LIMIT ?, ?

Can this SQL query be used for Oracle? Or this is MySQL specific?

Best wishes

Answer 1

Case1: If you want first `twenty Records` only then 

 select * from ( 
     select rn,a.*
     from Activesessionlogs a
     order by ??)
 where rn <=20
 order by rn

Case2:If you want the record between `5 to 10` then

select * from (
select rownum rn,e.* from Activesessionlogs e order by ??)
where rn >=5 and rn<=10 
order by rn 

Eg:
Lets find an example below

select * from (
select rownum rn,e.* from emp e order by hiredate)
where rn >=5 and rn<=10
order by rn asc

Note :Rownum> or rownum>= will not work in the same query .A very good blog explaining this Oracle Rownum