public static List<String> getCategories()
	{
		ResultSet rs=null;
		Connection con=null;
		PreparedStatement ps=null;
		List<String> result=new ArrayList<String>();
		try{
			String sql="SELECT * FROM category";
			con=ConnectionPool.getConnectionFromPool();
			ps=con.prepareStatement(sql);
			rs=ps.executeQuery();
			while(rs.next())
			{
				result.add(rs.getString("category_name"));
			}
		}
		catch(Exception ex)
		{
			ex.printStackTrace();
		}
		finally{
			if(rs!=null)
			{
				try {
					rs.close();
				} catch (SQLException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			if(ps!=null)
			{
				try {
					ps.close();
				} catch (SQLException e) {
					e.printStackTrace();
				}
			}
			if(con!=null)
			{
				try {
					ConnectionPool.addConnectionBackToPool(con);;
				} catch (Exception e) {
					e.printStackTrace();
				}
			}
		}
		return result;
	}