带子查询的外连接 (Oracle 11g)

Question

我需要一个到 table 的外部连接，它受子查询的限制。但是，Oracle 正在返回

ORA-01799: a column may not be outer-joined to a sub-query

然后我尝试将外部连接推送到另一个子查询中，但由于原始子查询依赖于主 table 中的一个字段，它正在连接到，这失败了

ORA-00904: "DTL"."TRANS_DATETIME": invalid identifier

谁能建议如何解决此连接？

查询：

SELECT *
FROM header  hdr
JOIN detail  dtl
    ON hdr.trans_number = ptd.trans_number
LEFT JOIN ( SELECT  product_code
                   ,cost_price
            FROM prodcost pr
            WHERE pr.last_amend_date = (SELECT MAX(pc.last_amend_date)
                                        FROM   prodcost pc
                                        WHERE  pc.product_code = pr.product_code
                                            AND pc.last_amend_date <= trunc(dtl.trans_datetime))) p
    ON ptd.product_code = p.product_code

说明我有 header 和 detail table 加入交易号（这实际上与问题无关，可以认为是单个 table）。然后我需要在 product_code 上离开加入 prodcost table。但是，我必须根据 trans_datetime

之前的最新 last_amend_date 来限制它

所以detailtable是一个交易记录，有产品ID（product_code）和交易日期（trans_datetime）。 prodcost table 记录了产品成本，其中包含产品 ID (product_code) 和生效日期 (last_amend_date)。因此，根据交易发生的时间，单个产品可能有多种成本。为了确定正确的成本，我需要 product_code link 和 trans_datetime 之前的最近 last_amend_date。

我知道我可以将其拆分为两个查询并 UNION 它们以提供完整的结果集。但是，如果可能的话，我宁愿避免这种情况。任何其他关于如何解决的建议将不胜感激。

Answer 1

这里有几个例子应该可以帮助你实现你所追求的目标（我自己编的 tables/data 因为你拒绝提供样本数据，但原则是一样的，你应该能够将其应用于您自己的查询）：

示例 1（使用左连接和分析函数）：

with t1 as (select 1 id, to_date('01/01/2016', 'dd/mm/yyyy') dt, 'a' val from dual union all
            select 2 id, to_date('02/03/2016', 'dd/mm/yyyy') dt, 'b' val from dual union all
            select 3 id, to_date('03/02/2016', 'dd/mm/yyyy') dt, 'c' val from dual union all
            select 4 id, to_date('04/01/2016', 'dd/mm/yyyy') dt, 'd' val from dual),
     t2 as (select 1 id, 100 val, to_date('01/12/2015', 'dd/mm/yyyy') dt from dual union all
            select 1 id, 120 val, to_date('12/12/2015', 'dd/mm/yyyy') dt from dual union all
            select 1 id, 130 val, to_date('04/01/2016', 'dd/mm/yyyy') dt from dual union all
            select 2 id, 200 val, to_date('01/03/2016', 'dd/mm/yyyy') dt from dual union all
            select 3 id, 300 val, to_date('04/03/2016', 'dd/mm/yyyy') dt from dual union all
            select 3 id, 330 val, to_date('06/03/2016', 'dd/mm/yyyy') dt from dual)
-- end of mimicking two tables, t1 and t2, containing data. See SQL below:
select id,
       t1_dt,
       t1_val,
       t2_val
from   (select t1.id,
               t1.dt t1_dt,
               t1.val t1_val,
               t2.val t2_val,
               t2.dt t2_dt,
               row_number() over (partition by t1.id order by t2.dt desc) rn
        from   t1
               left outer join (select id,
                                       val,
                                       dt
                                from   t2) t2 on (t1.id = t2.id and t2.dt <= t1.dt))
where  rn = 1;

        ID T1_DT      T1_VAL     T2_VAL
---------- ---------- ------ ----------
         1 01/01/2016 a             120
         2 02/03/2016 b             200
         3 03/02/2016 c                
         4 04/01/2016 d

示例 2（使用标量子查询）：

with t1 as (select 1 id, to_date('01/01/2016', 'dd/mm/yyyy') dt, 'a' val from dual union all
            select 2 id, to_date('02/03/2016', 'dd/mm/yyyy') dt, 'b' val from dual union all
            select 3 id, to_date('03/02/2016', 'dd/mm/yyyy') dt, 'c' val from dual union all
            select 4 id, to_date('04/01/2016', 'dd/mm/yyyy') dt, 'd' val from dual),
     t2 as (select 1 id, 100 val, to_date('01/12/2015', 'dd/mm/yyyy') dt from dual union all
            select 1 id, 120 val, to_date('12/12/2015', 'dd/mm/yyyy') dt from dual union all
            select 1 id, 130 val, to_date('04/01/2016', 'dd/mm/yyyy') dt from dual union all
            select 2 id, 200 val, to_date('01/03/2016', 'dd/mm/yyyy') dt from dual union all
            select 3 id, 300 val, to_date('04/03/2016', 'dd/mm/yyyy') dt from dual union all
            select 3 id, 330 val, to_date('06/03/2016', 'dd/mm/yyyy') dt from dual)
-- end of mimicking two tables, t1 and t2, containing data. See SQL below:
select id,
       dt t1_dt,
       val t1_val,
       (select max(val) keep (dense_rank first order by t2.dt desc) max_val
        from   t2
        where  t1.id = t2.id
        and    t2.dt <= t1.dt) t2_val
from   t1;

        ID T1_DT      T1_VAL     T2_VAL
---------- ---------- ------ ----------
         1 01/01/2016 a             120
         2 02/03/2016 b             200
         3 03/02/2016 c                
         4 04/01/2016 d

N.B。我假设 t1.id 是唯一的。

带子查询的外连接 (Oracle 11g)

Outer Join with Sub-query (Oracle 11g)

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