Question

我正在运行遵循父/子依赖项的delete语句块。执行该块时，一条语句引发完整性约束。但是，当单独执行该语句时，不会产生任何错误。

我已经逐步解决了依赖关系，并正确地将delete语句排序为从子级到父级。当一个或另一个不满足指示要删除记录的基本要求时，我添加了逻辑以包括父母或子女。

begin 
...
delete from rma_receipts where rma_detail_id in (select id from rma_detail where rma_id in (select id from rma where nvl(eplant_id, 1) in (1, 3)));
commit;
--constraint being triggered
delete from rma_detail where rma_id in (select id from rma where eplant_id in (1, 3));
... 
end;

不应清除任何约束，因为RMA_RECEIPTS中的所有子级都已清除。如果我分别运行两个语句，则不会产生任何约束。执行该块时，将产生此错误，表明无法删除rma_detail，因为rma_receipts记录引用了它。（但没有。）

    Error report -
    ORA-02292: integrity constraint (FK_RMA_RECE_REF_23860_RMA_DETA)         violated - child record found
ORA-06512: at line 60
02292. 00000 - "integrity constraint (%s.%s) violated - child record found" *Cause:    attempted to delete a parent key value that had a foreign
           dependency.
*Action:   delete dependencies first then parent or disable constraint.

为什么这会在一个区块中发生？而不是个别陈述？

Answer 1

一般方法：

delete from child_table where parent_key = ...
delete from parent_table where parent_key = ...

如果在两个步骤之间包含提交，则

容易出错。由于明智的时机，您可能会遇到以下问题：

会议1：

delete from child_table where parent_key = ...
commit

会议2：

insert a new row into child table for the same parent key

会议1：

delete from parent_table where parent_key = ...

您会收到一条错误消息，因为存在（新的）子记录。

解决方案很简单-删除提交。然后，取决于谁先进入，可能会发生两种情况。

会议1：

delete from child_table where parent_key = ...
delete from parent_table where parent_key = ...

会议2

tries to insert a new row - and will be blocked waiting for session 1 to either rollback or commit

OR

会议1

delete from parent_table where parent_key = ...

会议2：

insert a new row into child table for the same parent key

会议1：

delete from parent_table where parent_key = ...

，在会话2回滚或提交之前，会话1将被禁止删除父对象。无论哪种情况，最终都将删除所有父/子记录或保留所有记录，而不是损坏的混合物。

SQL块中的语句引发完整性约束，但不作为单个语句

1 个答案: