Question

我有以下数据库表：

在这些表中，我有以下要素：

容器：可以包含任何container_item元素;使用表CONTAINER_CANDIDATES
Container_Item：可以包含任何元素项;使用表COMPOUNDS
元素：我系统中的基本元素。

让我用一个具体案例来说明问题：

在ELEMENTS表格中，我可以存储以下元素：

Id = 1 ; ElementName = 'element001'
Id = 2 ; ElementName = 'element002'
Id = 3 ; ElementName = 'element003'
Id = 4 ; ElementName = 'element004'
Id = 5 ; ElementName = 'element005'
Id = 6 ; ElementName = 'element006'
Id = 7 ; ElementName = 'element007'

在表CONTAINER_ITEM中，我可以存储以下元素：

Id = 1 ; ContainerItemName = 'item-id-aaa'
Id = 2 ; ContainerItemName = 'item-id-bbb'
Id = 3 ; ContainerItemName = 'item-id-ccc'
Id = 4 ; ContainerItemName = 'item-id-ddd'
Id = 5 ; ContainerItemName = 'item-id-eee'

在表CONTAINER中，我可以存储以下元素：

Id = 1; ContainerName = 'ContainerName01';
Id = 2; ContainerName = 'ContainerName02';

使用表COMPOUNDS我进行以下连接：

    - item-id-aaa  (id = 1 in Container_Item table)
        -> element001 (id = 1 in Elements table)
        -> element002 (id = 2 in Elements table)
    - item-id-bbb (id = 2 in Container_Item table)
        -> element003 (id = 3 in Elements table)
        -> element004 (id = 4 in Elements table)
    - item-id-ccc (id = 3 in Container_Item table)
        -> element005 (id = 5 in Elements table)
        -> element006 (id = 6 in Elements table)
    - item-id-ddd (id = 4 in Container_Item table)
        -> element005 (id = 5 in Elements table)
        -> element007 (id = 7 in Elemens table);
    - item-id-eee (id = 5 in Container_Item table)
        -> element-007 (id = 7 in Elemens table)

使用表CONTAINER_CANDIDATES我建立了以下连接：

        - ContainerName01 contains the following :
            -> item-id-aaa (id = 1 in Container_Item table)
            -> item-id-bbb (id = 2 in COntainer_Item table)
            -> item-id-ccc (id = 3 in COntainer_Item table)
            -> item-id-ddd (id = 4 in COntainer_Item table)
        - ContainerName02 contains the following:
            -> item-id-aaa (id = 1 in Container_Item table)
            -> item-id-eee (id = 5 in COntainer_Item table)

所以通过这种方式我创建了所有的连接。现在的问题是如何删除ContainerName01及其下的所有项目（其下的容器项和元素），以便其他容器（例如：ContainerName02）完全不受影响？

我想使用Oracle PL SQL过程

来实现这一目标

Answer 1

如果你遵循良好的做法，这不是一个非常难的问题。

首先，你有两个“多对多”跳转表（CONTAINER_CANDIDATES＆amp; COMPOUNDS），因为这些中的孤立行将完全没用，我们将添加{{1在他们身上。

DELETE CASCADE

现在，事情几乎可以自行完成，这是一个小的存储过程，可以确保我们不会使用ALTER TABLE CONTAINER_CANDIDATES ADD CONSTRAINT FK_CC_CONTAINER FOREIGN KEY (CONTAINERID) REFERENCES CONTAINER (ID) ON DELETE CASCADE; ALTER TABLE CONTAINER_CANDIDATES ADD CONSTRAINT FK_CC_CONTAINER_ITEM FOREIGN KEY (CONTAINERITEMID) REFERENCES CONTAINER_ITEM (ID) ON DELETE CASCADE; ALTER TABLE COMPOUNDS ADD CONSTRAINT FK_COMPOUNDS_CONTAINER_ITEM FOREIGN KEY (CONTAINERITEMID) REFERENCES CONTAINER_ITEM (ID) ON DELETE CASCADE; ALTER TABLE COMPOUNDS ADD CONSTRAINT FK_COMPOUNDS_ELEMENTS FOREIGN KEY (ELEMENTSID) REFERENCES ELEMENTS (ID) ON DELETE CASCADE;和CONTAINER_ITEM并且我们很好。

ELEMENTS

这不确定你在任何一张桌子上都没有孤儿。它使用Cascade完成大部分工作，只需在两个从属表中进行一小部分未使用的数据。

唯一的缺点是如果你不使用它们，这将不允许你继续进入CREATE OR REPLACE PROCEDURE cascaded_delete_container ( P_CONTAINER_ID VARCHAR2 ) IS BEGIN -- remove the master from supplied ID -- cascade on CONTAINER_CANDIDATES DELETE FROM CONTAINER WHERE ID = P_CONTAINER_ID; -- remove CONTAINER_ITEM not used in CONTAINER_CANDIDATES -- cascade on COMPOUNDS DELETE FROM CONTAINER_ITEM WHERE NOT EXISTS( SELECT 1 FROM CONTAINER_CANDIDATES WHERE CONTAINER_ITEM.ID = CONTAINER_CANDIDATES.CONTAINERITEMID ); -- remove ELEMENTS not used in COMPOUNDS DELETE FROM ELEMENTS WHERE NOT EXISTS( SELECT 1 FROM COMPOUNDS WHERE ELEMENTS.ID = COMPOUNDS.ELEMENTSID ); COMMIT; END; /和CONTAINER_ITEM。

Answer 2

如果要通过一个过程实现这一点，那么可以将容器ID作为参数传递，然后删除通过游标获取的子条目。据我了解，您需要先删除CONTAINER_CANDIDATES和COMPOUNDS表中的条目。例如：

create or replace procedure delete_container(p_container_id number) is

  -- Get all compound child etries via container ID
  cursor c_get_compounds(cp_container_id number) is
    select comp.id
      from compounds comp, container_candidates cc
     where comp.containerItemID = cc.containerItemID
       and cc.containerID = cp_container_id;

  -- Get all container candidate child entries via container ID
  cursor c_get_container_candidates(cp_container_id number) is
    select cc.id
      from container_candidates cc
     where cc.containerID = cp_container_id;

begin

  -- Fetch all compound entries
  for r in c_get_compounds(cp_container_id => p_container_id) loop
    -- Delete compound entries
    delete from compounds where id = r.id;
  end loop;

  -- Fetch all container candidates
  for r in c_get_container_candidates(cp_container_id => p_container_id) loop
    -- Delete container candidates
    delete from container_candidates where id = r.id;
  end loop;

  -- Delete container entry
  delete from container where id = p_container_id;
end delete_container;

检查代码中的ID是否正确

更新数据库表

2 个答案: