oracle8.1.6 select unique u.user_id, first_names, last_name from cc_users u, ec_items i, ec_orders o, ec_products p where i.order_id=o.order_id and o.user_id=u.user_id and i.product_id = p.product_id and p.sku=:product_sku select unique u.user_id, first_names, last_name from cc_users u, ec_user_session_info ui, ec_user_sessions us, ec_products p where us.user_session_id=ui.user_session_id and us.user_id=u.user_id and ui.product_id = p.product_id and p.sku=:viewed_product_sku select unique u.user_id, first_names, last_name from cc_users u, ec_user_session_info ui, ec_user_sessions us where us.user_session_id=ui.user_session_id and us.user_id=u.user_id and ui.category_id=:category_id