Question

有两个表格：M_LINK和M_LINK_DATA。

CREATE TABLE M_LINK (
    ID             INTEGER NOT NULL,
    ISDIRECTED     SMALLINT DEFAULT 0 NOT NULL CHECK (ISDIRECTED IN (0,1))
);

CREATE TABLE M_LINK_DATA (
    ID           INTEGER NOT NULL,
    LINKREF      INTEGER NOT NULL,            -- reference to any record of table M_LINK
    MAINRECREF   INTEGER DEFAULT -1 NOT NULL, -- reference to any record of some third table
    SUBRECREF    INTEGER DEFAULT -1 NOT NULL  -- reference to any record of some third table
);

我想选择SUBRECREF M_LINK_DATA的所有LINKREF，其中:linkref是M_LINK的特定记录MAINRECREF，:recref是特定记录第三个表的select SUBRECREF from m_link_data where LINKREF = :linkref and MAINRECREF = :recref。到目前为止，非常好。

这是我的SQL语句：

ISDIRECTED

此外，如果来自:linkref的记录M_LINK的{{1}}等于0，则结果还应包含MAINRECREF M_LINK_DATA的{{1}} {}} { {1}}与已知第三表的特定记录SUBRECREF相同。

示例数据

:recref

所需的输出

代表-----M_LINK---- ID | ISDIRECTED ---+----------- 1 | 1 2 | 0 -------------M_LINK_DATA------------- ID | LINKREF | MAINRECREF | SUBRECREF ---+---------+------------+---------- 3 | 1 | 10 | 11 4 | 1 | 10 | 12 5 | 1 | 13 | 10 6 | 2 | 10 | 11 7 | 2 | 14 | 11 8 | 2 | 13 | 10 9 | 2 | 15 | 10和:linkref = 1：

:recref = 10

代表RECREF ------ 11 12和:linkref = 2：

:recref = 10

如您所见，应该只有一个结果列，包含RECREF ------ 11 13 15或MAINRECREF。

请帮我扩展我的SQL查询以考虑SUBRECREF。

Answer 1

I'm not sure if I understood correctly but this procedure returns the desired result:

create or alter procedure NEW_PROCEDURE_2 (
    LINKREF integer,
    RECREF integer)
returns (
    O_SUBRECREF integer)
as
declare variable V_MAINRECREF integer;
BEGIN
  FOR
    select 
        t.subrecref,t.mainrecref
    from m_link_data t
    where 
       (
          (linkref = :linkref)
       and 
          (mainrecref = :recref)

       or
      (
      (linkref = :linkref)
      and
      ((select t1.isdirected from m_link t1 where (t1.ID = :linkref)) = 0)
      and 
      (t.SUBRECREF = :recref)
      )

       )
    INTO :o_subrecref,
         :v_mainrecref
  DO
  BEGIN
    if (:o_subrecref = :recref) then  o_subrecref = :v_mainrecref;
    SUSPEND;
  END
END

Answer 2

您可以使用单个查询执行此操作，而无需通过在主方向的查询和反向的查询之间使用联合来诉诸存储过程。

with directed_links as (
    select ld.linkref, ld.mainrecref as origin, ld.subrecref as target
    from m_link_data ld
    union all
    select ld.linkref, ld.subrecref as origin, ld.mainrecref as target
    from m_link_data ld
    inner join m_link l on l.id = ld.linkref
    where l.isdirected = 0
)
select target
from directed_links
where linkref = :linkref and origin = :recref

如何选择包含特定记录引用的定向链接和无向链接

2 个答案: