sql - 子查询返回多个值

Question

我有以下查询，它给出了 req_no 和 order_no。 order_no 是来自 sub_query 的，您可以从下面的 sql 中看到。对于一些 req_no，有多个 order_no，因此我得到了 ORA-01427: single-row subquery returns more than one row .

我想为一个 req_no 同时显示 order_no，我该如何实现？ 非常感谢任何帮助。

谢谢

附言我们客户的一个数据库仍然是 Oracle 8i。

SELECT  max_qst.req_no,
            (SELECT  DISTINCT max_odr.order_no
                FROM     maximo_orders max_odr,
                         maximo_order_revisions max_odv,
                         maximo_order_items max_odi,
                         maximo_order_dates max_odd,
                         maximo_requisition_order max_rqo,
                         maximo_requisition_details max_req
              WHERE       max_req.req_no = max_qst.req_no
                         AND max_req.req_yr = max_qst.req_yr
                         AND max_odr.order_no = max_odi.order_no
                         AND max_odi.order_item_id = max_odd.order_item_id
                         AND max_req.requisition_item_id = max_rqo.requisition_item_id
                         AND max_rqo.order_schedule_id = max_odd.order_schedule_id
                         AND max_odv.order_no = max_odi.order_no
                         AND max_odv.revision_no =
                                 (SELECT   MAX (max_alias.revision_no)
                                     FROM   maximo_order_revisions max_alias
                                    WHERE   max_alias.order_no = max_odv.order_no)
                         AND maximo_order_item (max_odi.order_no,
                                                                  max_odv.revision_no,
                                                                  max_odi.order_item_id
                                                                 ) = 'CONFIRMED'
                        )
  FROM  maximo_requisitions max_qst, maximo_requisition_details max_qsd
 WHERE       max_qst.qst_id = max_qsd.qst_id
            AND max_qst.enter_date = '2001'
            AND max_qst.req_no = 'PUR_12WX'

更新 1

期望输出。

REQ_No     ORDER_NO

PUR_12WX   PR_9078  
PUR_12WX   PR_9079  

Answer 1

使用连接而不是相关的子查询。

我已经从子查询中删除了 max_qst 引用并将它们移动到连接谓词。

我也刚刚将其更改为使用 LEFT JOIN。这允许没有返回 order_no 值的可能性。

SELECT
  max_qst.req_no,
  sub_query.order_no
FROM
  maximo_requisitions          max_qst
INNER JOIN
  maximo_requisition_details   max_qsd
    ON max_qst.qst_id = max_qsd.qst_id
LEFT JOIN
(
  SELECT DISTINCT
    max_odr.order_no,
    max_req.req_no,
    max_req.req_yr
  FROM
    maximo_orders              max_odr,
    maximo_order_revisions     max_odv,
    maximo_order_items         max_odi,
    maximo_order_dates         max_odd,
    maximo_requisition_order   max_rqo,
    maximo_requisition_details max_req
  WHERE
        max_odr.order_no            = max_odi.order_no
    AND max_odi.order_item_id       = max_odd.order_item_id
    AND max_req.requisition_item_id = max_rqo.requisition_item_id
    AND max_rqo.order_schedule_id   = max_odd.order_schedule_id
    AND max_odv.order_no            = max_odi.order_no
    AND max_odv.revision_no         = (SELECT MAX (max_alias.revision_no)
                                         FROM maximo_order_revisions max_alias
                                        WHERE max_alias.order_no = max_odv.order_no)
    AND maximo_order_item (max_odi.order_no,  max_odv.revision_no, max_odi.order_item_id) = 'CONFIRMED'
)
  suq_query
    ON  max_qst.req_no = sub_query.req_no
    AND max_qst.req_yr = sub_query.req_yr
WHERE
  max_qst.enter_date = '2001'
  max_qst.req_no = 'PUR_12WX'